Reports for July, 2001
A Night under Moon and Stars
A Dog's Day Night...
The Difference a Night Makes
Back on Track
Ares Unsheathed
Rings Anyone?
Argo's Favorite Globular Cluster
If it Ain't the Moon - It's the Clouds...
Help From an Unexpected Quarter...
Oh Yes, Where Was I?
Fire in the Sky
A Vague Sense of Frustration
Galaxy Quest Continues
Takes a Darker Night
Mars is Back! For How Long?
Odds 'n Ends
SCAC Star Party Potpouri
Pacific Ocean Marine Layer Subsides
But for a Stable Southern Sky
Sky and Mars Refuse to Dance!
A Less Than Inspiring Night Out
Refreshed and Rejuvenated
Best Layed Plans
Making Good Out of Bad
Synchronicity Strikes Again!
Reports for September, 2001

A Night under Moon and Stars

Another clear night for Backyard, Boulder Creek (ho hum). Started out by turning Argo on Mars and Antares. Seeing stability not quite as good as last evening. (I give it 5/10 some 30 degrees above the south horizon.) Mars displayed a somewhat muted "smile" of limb haze. Polar brightenings apparent - but lacked that "illusory bulge" visible on better nights. (Something most often seen with the SPC.) A vague "rakish cap" of faint maria ran down from sub-SPC earth-east to equatorial earth-west. Hints of maria rimmed the NPC. The planet appears exceedingly gibbous and has lost about a quarter of its full-opposition size. Viewing it sans filter is also easier - due to reduced surface brightness. As long as Mars remains near culmination, I'll continue to monitor for that one last ecstatic view - hopefully this becomes possible as the planet climbs out of the well of the southern ecliptic.

Antares is now definitely past culmination. I continue to monitor the star for the same reason I follow Mars. There is always the chance that its spurious image will collapse enough to show a secondary bearing an airy disk. Meanwhile, I can continue to accumulate data on how southern sky stability tracks against that seen overhead...

The Moon remained safe behind the southeast foliage until around 10:00. As you might expect given the phase, the view was less than thrilling. Much too bright, very low feature contrast, and through this particular sky, less than finely hewn. Couldn't push beyond 180X. Spent the majority of my time rounding up the usual lunar suspects - Plato, Posidonius etc. Then spent a few moments contemplating the enormous ray-structures of Tycho et al. Again this evening, placed the red filter between eye and image - even so ended up with a huge black disk of blown-dark adaptation that took 5 or 10 minutes to dissipate.

While regaining my optical composure, setup Argo on the north observing station. The Double Double was resolvable - but displayed that "egg-shaped" luminosity which occasionally encompasses the stellar disks. View through the 80mm Pup showed this too. Must have been a lot of water vapor in the air. Transparency limited to about magnitude 4.2 ZULTM. The sky shot through with fine silvery threads of near full moonlight...

The Pup showed the 12.5 magnitude star between the Doubles on eye movement. Argo picked up the 13.8/9 stars under the same conditions. At the Ring I could hold the 13.0 star with moderate aversion. So direct telescopic limiting magnitude was roughly 12.3.

The Ring itself was washed out. Stars seem to be less impacted by moonshine than nebulosity. (No surprise here.) Again though, there are a lot of good reasons to make nebulae quests during moontide. High among them is eye-training for finding 14th magnitude surface brightness studies later on under truly dark skies... Turned Argo on Eta Draconis. At lower magnifications, kept seeing a faint blue star trailing and to the south. Bumping up the magnification showed nothing. If I didn't know the companion fell to the north, and had only inspected at lower magnifications, probably would have reported this as the secondary. Disparate doubles can be very deceptive. Check and recheck...

Then on to STT2950 in Cepheus. Easy find this one - four degrees almost due south of Iota. Easy split too - despite the 6/10 seeing overhead The 7.1 magnitude companion lay almost due west of the 6.1 magnitude primary. Split suspected at 180x. Clear at 210. 1.4 arc-seconds is about right (although it could be a tad wider if anything). No trouble directly holding both stars. It's clear (from both Pi Aquilae and STT2950) that a single magnitude difference in stellar components - even under close proximity- is no challenge to the eye.

Despite less than ideal seeing, tracked down 4.8/6.3 .9 arc-second STT413. Could immediately tell that this was a double. Also figured its orientation - north-south. But couldn't distinguish one component from the other. Simply too much "star goop" (the stuff seen around the Double-Double). Strangely I would have guessed the dimmer star lay to the south - not the north as based on 1999 data. Given this initial impression, I don't think I am going too far out on a limb to say that this pair is resolvable - defined as clean separation with both components held direct - on an 8/10 stability night.

This was around 11:30pm. Time to put away the scopes and call it a night under moon and stars.

A Dog's Day Night...

Absolutely no enthusiasm for observing last night - cells needed a break. BUT on the off-chance that Ares unsheathed, took a look at Mars... Seeing stability quite poor (couldn't even get a decent 210X view). What I did see suggested that maria obscura may have been in abeyance. Worth another look tonight.

Double Double a messy split - but split nonetheless. Again "egg foo yung" connecting the two pairs. 12.5 mag star could be held but nothing of the 13.8/9. Stability do have a significant impact on magnitudinal reach...

Dwelled on 2.8 magnitude Eta Draconis for awhile. By bumping the mags way up, could make out an airy disk. But unlike under better conditions, that disk was "enflamed" and restless. No sign of 8.2 magnitude companion 4.8 arc-seconds to the southeast (1996 PA=139 degrees).

Woh back??? Did I just write "southeast"? So I DID see the companion at lower powers the other evening! (I just realized this in looking over data sent to me by fellow observer Cor Berrevoets.

OK, I may not have been too excited last night - but I am now. Hold on a sec - let me check the last report...

There it is: "kept seeing a faint blue star trailing and to the south". Eta, I'm glad I met ya! (And this goes on to demonstrate that you just have to use the lowest magnification possible to make out these disparate doubles - even on the best of nights. And of course, don't always believe what you think!)

OK, so back to the desultory tale of last night...

Kept doggedly viewing Eta until the Moon finally cleared the trees. Then switched Argo back over to the south viewing station.

Stability still poor. Maxed out at 180X. Lunar rays all over the place. Crater Aristarchus (to the northeast) was    B R I L L I A N T   and almost comet-like with its short, stubby, but almost equally brilliant tale. Tycho wrapped its chalky tentacles almost a quarter-way around the globe. (The double paralleling rays very prominent.) Then, on a tip from fellow observer theAstronomer, checked out Pythagoras and got a "distant view" of this large crater's double peaks projecting well-above the limb to the north-northeast. Not bad and worthy of a better night at higher magnification...

And that was it. Definitely ready for a dark sky night! But in the least, IF the moon is going to hang around - a steady enough sky for some serious double star quests...

The Difference a Night Makes

As you might guess, I found last night's observing session less than inspiring. Between lunar floodlighting and a less than stable sky observing options were extremely limited. Oh were I a better stargazer! Then I could fall into "mystical rapture" even at the sight of the most bloated and flaring star. But alas, I am an admitted scopist and find it almost painful to look upon a heavens embattled by sky conditions and the light pollution of a dead world tethered to our own by the immutable laws of mutual gravitational attraction.

As indicated in the last report, Mars seems to be showing some of its old spunk... No, not a true wake up - but at least some features lying in the planet's equatorial region are now at least possible. Again I am struck by the lack of correspondence between the image in MarsPreviewerII and what I've sketched. Certainly there was nothing particularly "contrasty" in the few hints of maria seen on the planet the last few times but again I've been as faithful as my limited views and drafting skills are capable of...

Antares played with me as well. At 210X I could make out the largish airy disk of the star. There were also several diffraction rings and the usual flaring and flashing. Certainly the diameter of all this was in the range of 5 - 6 arc-seconds. Because of this the companion was in constant jeopardy. Again use of any kind filter (red even!) really helps to reveal the companion...

If you read my last report you may have caught my excitement at learning I had actually seen the closish (4.8 arc-second), faintish (magnitude 8.2) companion to brightish (2.8 magnitude) Eta Draconis several nights back. At that time, and for some inexplicable reason, I had misremembered the companions position angle and assumed Eta-B was northeast rather than southeast of the primary. Well prepped with the facts, I revisited the pair and was able to verify that earlier observation - this time at 210X. In so doing I took a few moments to compare the relative difficulties of Eta to Polaris and Delta Cygni. By far Polaris-B was the easiest of the three faintish secondaries to make out. This despite lower sky position (<40 degrees) and presence in the worst of the Boulder Creek Lightdome. Meanwhile, Eta and Delta's companions are on par for difficulty. An important fact given that Eta-B is found about twice as distant from the primary and is roughly 4 times dimmer than Delta-B. Very useful information indeed...

Now I had already visited with the Double Double. All four stars were tiny jewels set in beautiful and complete single diffraction rings. So I suppose it was unnecessary to turn up Pi Aquilae, but I did anyway. At one half the separation (1.4 arc-seconds) of Epsilon-2 and dimmer by probably 1 magnitude, this pair could be cleanly and unquestionably resolved at 210x. It will be very interesting to see if the 80mm Pup can resolve this pair on a similar night at maximum power (some 270X).

Lingering doubts continue to accompany thoughts regarding .9 arc-second +2 magnitude delta, BU63 in Delphinus. So tonight I scrutinized this pair again as a check against self-delusion. Again at maximum power (540x) I was able to see that there was clearly something "wrong" with the sixth magnitude pale blue-white primary. Again I thought I could catch a very faint brownish-yellow companion pendent from the primary to the north-northwest. There really was no way to distinguish one star from the other - but I could, at minimum, determine the position angle of the companion.

So, effectively a quality 150mm scope meets its match when attempting to resolve two stars less than 1 arc-second apart where one star is 2 magnitudes (greater than 4 times) dimmer than the other. But where is the line?

Earlier in the week, I tracked down a double star in Cygnus (STT413) where the primary is of magnitude 4.8 and the secondary 6.3. This gives a delta of 1.5 magnitudes (4 times dimmer) and would make a nice test case for a lower limit disparate magnitude pair very close to the Dawes limit for a 6 inch scope (~.8 arc-seconds). On that occasion I was pretty confident that a clean split was possible but seeing stability was marginal (7/10) and I needed a better night.

Tonight was that night. And yes, despite a pair of brightenings on the single diffraction ring of the primary, I was able to cleanly distinguish the brownish-yellow 6.3 magnitude companion due north of a very attractive radiant blue-white primary. This, of course, was only possible at 540X.

With this most agreeable observation, I felt my night was complete. However, there was still the matter of the moon. The quality of the night sky was such that I suspected Selene would reveal herself - rather than the dreadful Hecate... But it would be at least a half-hour before Luna would clear the foliage to the southwest. So I lay on my back on the work-out desk contemplating Capricorn hoping I might get a late hit from the Capricornid meteor shower. Nothing doing...

By carefully repositioning Argo near the edge of the deck I was able to get an early-bird view of the globe. Selene was in full display. Nice sharp edge. Decided to revisit the haunts of the last few weeks. Almost able to cleanly split the twin mounds in Posidonius. Easily distinguished the small twin craters west of brilliant Aristarchus. Caught "Ernie" near Birt. No sign of the Straight Wall. Pythagoras Twin Peaks invisible to me. Plato showed, at best, a single brightening near the center. And the dark effluvia bordering Mare Serenitatus quite prominent.

This will be my last view of the Moon for this cycle. Likely as not I'll have packed Argo away and been well ensconced in bed by the time she clears the foliage - until she once again completes her round and waxes once again to fullness...

Back on Track

There really was no true "skydark" this evening. Just as the deepest veils of night began to descend, the Moon cast her net of silvery light over the evening. Despite this, I was able to continue (with some real joy) advancing the year-long observing plan.

By 9:15 I had had my fill of Mars. Southern sky stability limited magnification to 210X - max. There was no way to set focus on the planets limb. A vague gash of low contrast maria descended from the planet's southern hemisphere to the equator. Best views without filtration. Despite the last months increasingly poor views I'll hang in there with the Red Planet until it's past culmination in the early evening sky...

Knowing the Moon would soon rise, I started scanning Sagittarius early on in the evening through the finderscope. The idea was to find some feature (other than a star) that I could use as a "touch-study" for contemplation until the sky darkened enough to move on.

Turned up M7 - north of the Scorpions Tail. With many of the dimmer stars overpowered by the early evening sky, only the brightest three or four dozen members were visible. Among these were a dozen seventh and eighth magnitude stars that in total bore a striking resemblence to the constellation Hercules. In watching the asterism it became clear that the demi-god's feet were to the west and head was to the east. So in Argo's field the asterism moved feet first laterally across the field of view.

Initially wasn't completely sure it was M7 that I was regarding. To confirm I swung Argo due east and verified the cluster's position due west of Epsilon and Nu Sagittari. From there it was easy enough to move north and west to Gamma. From Gamma a quick stint due north revealed the Lagoon Nebula and Strawberry Cluster in the finder field. Amazingly, even through a 4.0 ULTM sky, nebulosity could be clearly made out - especially west of the cluster.

Despite a thorough search of the finder field, I was unable to locate the Trifid nebula. And without the vague haze of the Trifid to guide me, I couldn't even locate the two eighth mag stars associated with it. (One of which is a multiple star system of some real beauty and interest.)

By this time the sky got about as dark as it was going to get. Now was the time to document three "fresh finds" - two globulars and an open cluster.

The first was 8.3 magnitude / 5.7 arc-minute sized NGC6624 located 1 degree southeast of Delta Sagittari. To be accurate, I had turned this cluster up previously - during a preliminary survey of the region. (About a week ago while attempting to track down Asteroid Ceres near Globular Cluster M54.) Despite the less than favorable transparency of the evening, the cluster was easily found as part of a west-northwest line of two equally separated seventh magnituude stars. At 70X, the cluster displayed 2 arc-minutes of its south-southwest to north-northeast elongated core region. A starlike point discernable. At 180X, the cluster flared noticeably southeast and the center point shifted north. A general flattening could be seen to the east-northeast. Several eleven plus magnitude stars were found in the outlier region of the cluster. None likely to be actual cluster members. Despite the "greyness" of the sky, could sense the characteristic "blueness" of all globular clusters...

As easy as the 8.3 magnitude NGC6624 was, only slightly dimmer (magnitude 8.7) and equal-sized NGC6569 was not. Under 4.5 ULTM conditions, this 12.2 average surface brightness globular was quite washed out. No sense of core region possible. On direct vision, could see a vague central brightening dissipating outward perhaps 1.5 arc-minutes. This blended into the general murk of the sky. While NGC6624 presented itself credibly at 180x, made no attempt to examine 6569 under any other magnification. Despite the vagueness of the cluster, could discern a slight southeast-northwest oblation to its glow. Due to unexpected dimness, I made a quick check through the finderscope to ensure I was in fact in the required sky location. Yup, there I was, nicely triangulated south of Delta and Gamma Sagittari...

From 6569 it was easy enough to turn up M24 and my next NGC study - 11.1 magnitude, 5 arc-minute sized open cluster NGC6603. Had I known how dim this study was probably never would have made the attempt. All I knew at the time was that it was on my charts and should be easy enough to turn up since it lay within the glorious star-studded confines of the M24 star field.

My first sweep through M24 revealed several vague hazes. Some no doubt were star birth nebular glows, others concentrations of the field itself. The question remained: Which was NGC6603? The situation was pretty hopeless. So I did something I really try to avoid - made reference to text in Harrington's "The Deep Sky" for clues as to its location.

Now over the last year this particular volume has been both a blessing and a curse. For one, the guy's about as dyslexic as I am - citing west when he means east (Intergalactic Wanderer anyone?) and generalizing too imprecisely about distances between reference points (NGC206 within M31). Finally, and perhaps most dangerously to me - leaving off a number of Messier studies from the book's star atlas. Despite this the work remains my constant nocturnal companion...

Last night, however, Harrington did a "bang up job" of precisely describing the location of NGC6603. And this description (aim at the easternmost star of the M24 "kite" and shift 13 arc-minutes north) fit the bill. But some things he forgot to mention... The easternmost star of the kite is actually a lovely double star. The sixth mag golden yellow primary leads the seventh magnitude aqua secondary across the sky (and to the south by about 6 arc-seconds).

The cluster itself - as you might suspect - was little more than a vague sheen against the star field. Absolutely no resolution of member stars possible - even at 180x. At that magnification, only the vaguest scintillation possible. Meanwhile the cluster took on a distinctly linear appearance. It is likely that only the clusters' extreme density rendered it detectable this evening - even as the Moon shone through the foliage in the southeast...

In a few days I'll be visiting with M24 in earnest. There is no doubt that I'll want to revisit this cluster and other areas of interest within its copious confines...

Ported Argo over to the north viewing station. Made a quick check of Eta Draconis at 120X and 210X. Yup, "lower is better". The effect of magnification on disparate doubles is significant. At 120X, dim but unambiguous. At 210X - difficult - if not illusory... However, at the lower magnification, the 8.2 magnitude secondary lay just outside the 2.8 magnitude primary's spurious image. So there is a lower limit to useful magnification - especially with the tighter pairs like Antares, Eta Draconis and Delta Cygni.

Checked the Double Double at 180X. Sky stability overhead 7/10. Single diffraction rings with some slight "egg foo yung" between members. Not the precise gems of confined luminescence seen under 8/10 conditions. 12.5 mag come held direct between pairs. Dropping down to 70X, it was clear that both pairs were visibly elongated. On an 8/10 stability night, the more closely matched E2 pair is hair-line separable.

At the Ring, the 12.8 magnitude test star could be held direct - as a star - not a diffuse blob. 13.0 could not.

Overall a shorter night of observation than usual. But, frankly I've squeezed as much as I can get out of this lunar cycle and need to recharge for the (hopefully) dark and steady skies ahead. Skies that should yield up the rich bounties of the Milky Way from Sagittarius to Cygnus.

If the lunar second quarter teaches anything, it teaches forbearance and rapturous appreciation for the night sky in its abscence. Fare-the-well Moon, see you in a couple of weeks.

Ares Unsheathed

Due to a slight change in schedule, The Ageless Jazz Quartet's Sunday evening performance at the World Famous Book Room (- they have ghost you know...) ended half an hour later than last week. After a shakey first set, the band pulled itself together for a solid second and nailed the third. A gig like this should have been enough for one evening. And it most certainly would have - had the Moon been visible upon return. But it wasn't, and the sky looked enticingly dark and stable. Mars lay near culmination. I multitasked putting away musical equipment and taking out the scope. By 9:30, I was at the eyepiece - quickly scanning Antares for tube currents (yes, some) and the presence of a companion. (Again the faded moth dancing around the primary's flame.) Sky conditions were favorable. All that was now needed was a little cooperation from the Red Planet...

And the Red Planet came across. The sketch (and the view of the planet this evening) seems to suggest Syrtis Major - but this is not the case - at least based on MarsPreviewerII software. By fiddling with parameters, my best match was Time Zone +6 GMT, 19:00 hours, August 4, 2001. As such Mare Erythraeum has progressed Mars-east of the central meridian. It constitutes the bulk of the thumblike projection into the equatorial region. By this reckoning, the brighter region Mars southeast of Erythraeum is Pyrrhae Regio. Mare Boreum can be seen vaguely collaring a diminished North Polar Cap. Niliacus Lacus and Mare Acidalium are suggested beneath Erythraeum (and above Boreum). Eartheast of Erythraeum is a vague linear darkening that terminates in Tithoneus Lacus. Above that, lies the Sinai desert region. Still further south, Solis Lacus is seen and bordered in turn by a vague brightening (Thaumasia) - itself surmounted by a darker Bosporos Gemmatus. Like the North Polar Cap, the SPC was less than dominating.

Took one look at the planet at 540X (sans filter). Despite reasonable edge focus, a dearth of detail - although the polar caps and mars-eastern limb haze was easily made out. 360X supported the blue filter quite nicely. As such the Erythraeum region became noticeable - along with brightish Pyrrhae Regio. There was also a hint of darkish Acidalium and Boreum. 210X was reserved for red filter use and detailed maria inspection. Spent the bulk of my time viewing the planet through this filter - mostly because "blue brightenings" are easier to locate and draw than "red darkenings".

Despite a decent view of the planet, I remained mindful of an impending Moonrise. By 10:00 PDST - and with sketch complete, switched over to deepsky. Tracked down 7.7 magnitude 7 arc-minute sized M69. Followed this study with 8.5 magnitude 10 arc-minute open cluster NGC6645. Then off to find! the large (10 arc-minute) 9.4 magnitude galaxy NGC6822. Closed out the series of new studies with small 10x5 arc-second 10.5 magnitude planetary NGC6818.

Globular M69 gives a general appearance similar to M80. Small, compact, moderately bright, and generally unresolvable. The cluster sits about 6 arc-minutes southeast of a bluish 7th magnitude star. Proximity to the star makes detection through the finderscope difficult. The 70X view was "rough" with incipient resolution. About half the clusters documented size was visible direct. The typical star-like core not seen, however. In its place, a round, bright core center, surrounded by a distinct core region. Flaring seen to the southeast on eye movement. Corresponding to flare was a sense of flattening to the west. I half expected to get some resolution at 180X - but this didn't quite pan out. Sure the sky could have been darker (ULTM=4.8) and higher sky position would have been a boon (local sky stability ~ 5/10). But there was a distinct sense of dozens of resolvable members hovering just beyond the limiting threshold magnitude of the sky and scope. What may be two 13th mag outliers "scintillated" perceptibly.

Generally I don't prefer to document Messier studies through less than ideal skies. Stability was as good as you can get - some twenty degrees above the horizon. However, the Moon had already forecasted its arrival - despite having yet to rise. I look forward to viewing M69 again. It should make a nice comparison to see it as the Moon approaches the fourth quarter.

It may seem strange but I prefer to tackle NGC studies during moontide. This particular "lunacy" comes out of the fact that a parallel project I'm working requires definitive views of Messiers. So after characterizing M69, I shifted over to the three NGC's. First stop: Star Cloud M24 - and the 11.1 magnitude open cluster (NGC6603) which lies within it. Frankly, yesterday I was surprised that I could detect anything of an open cluster whose brightest members are of the 14th magnitude. Now, this kind of thinking kills. Despite finding the marker double of the previous evening, I was unable to make out the vague haze of the cluster against the richly endowed backdrop of innumerable stars. Like M69, this one deserves another viewing...

From M24, moved north to the Swan Nebula. Contemplated this lovely vision then slewed a few degrees east and slightly south to 8.5 magnitude open cluster NGC6645. Now those who have followed this series may recall difficulties had turning up open cluster NGC1245 in Perseus early in the year. NGC1245's integrated magnitude of 8.4 is very close to the 8.5 of NGC6645. Both clusters have an apparent size of 10 arc-minutes. By the numbers, these clusters share an average surface brightness of magnitude 13. All this suggests that, under the 4.8 ULTM conditions of the evening, locating NGC6645 should have been near impossible...

Well as it turned out, not only could the cluster be found - but it actually gave a pretty decent view. What first caught my eye (through the 70X eyepiece), was a vague haze sprinkled with perhaps two dozen 11th and 12th magnitude stars. This group gave the general appearance of a "hobby horse" - head - west, haunches - east, hooves - north. East of the "hobby horse", a 40 arc-minute line of four or five 7th magnitude stars shot down from the south - nearly brushing the cluster. On the centerline of the cluster and to the west was a faint double star. The double's tenth magnitude primary was, in fact, the brightest member of the group. It's eleven plus magnitude companion trailed some 5 arc-seconds west. Frankly, due to proximity to the brighter star, the companion was a bit dim for direct view. Bumping the magnification up to 180X helped but even so, it was still a difficult hold. However, at that higher magnification perhaps three dozen cluster members were possible under averted vision...

To locate my next pair of studies required an 8 degree slew due east to Rho Sagittari - the little tea spoon above the teapot. From Rho, a quick jaunt north to a neighboring fifth magnitude finderscope field star, then east again another 3 degrees to a broken crescent of four fifth and sixth magnitude stars that mark the region of Galaxy NGC6822 and planetary NGC6818.

The planetary was an easy find. Meanwhile, the Moon had already visibly brightened the sky to the south. So I tried for the 10 arc-minute sized 9.4 magnitude galaxy first. Now you may first ask, "What the heck is a galaxy doing this close to the Milky Way?" The answer: "Making itself as inconspicuous as possible." At best I was able to imagine a large, vague, roundish patch of luminescence slightly brighter than the quickly brightening night sky. So, like the 11.1 magnitude cluster in M24, I'll be revisiting 14.1 magnitude average surface brightness Galaxy NGC6822 real soon...

As mentioned, the planetary was a cinch. Even with a sky rapidly approaching deepsky minimum (4.5 ULTM), it was an easy find. What piqued my interest was the sense of "annularity" about it. Even at a lowly 70X, this 10 arc-second sized disk of pale blue-green light seemed to have a center punctuated by a small pinhole of darkness. More obvious was the impression of a central star - and if not a "star", then at least, an luminous core due to ones presence. Inspection at higher magnifications (to 180x) never quite revealed either the star or the hole - but it did help reinforce the validity of the impression.

I continue to be engaged in evaluating challenges associated with doubles of disparate magnitudes. These range from Antares (1.3/5.4 2.4 arc-seconds), to Delta Cygni (2.8/6.4 2.4 arc-seconds) through Eta Draconis (2.8/8.2 4.8 arc-seconds). Each is equally difficult. Due to low sky position, I am least likely to catch an unambiguous view of Antares-B. Historically, and even under 6/10 local seeing stability, I rarely catch a solid look at this particular companion. Meanwhile, as Delta Cygnus proceeds towards culmination, its difficulty lessons - but still requires a solid 7/10 overhead stability sky and higher magnification for a sensible view. Eta Draconis is not as favored as Delta for sky position. 7/10 stability reveals Eta-B but only to lower magnifications (120X).

All three pairs were possible tonight - none easy. Concentration and patience, the key...

Meanwhile the Double Double was a nice clean split. Interestingly, the 12.5 come was a wee bit hard to hold direct while the 13.8 comites could be seen on eye movement. However, by the time I moved on to the double star / magnitude test series the Moon was well above the southeast horizon.

Ring testing showed that the 13.08 star east of the planetary's ansae could be held with the slightest aversion. Meanwhile, eye movement would occasionally show the 14.6 magnitude star flanking the ring to the north. 180X is normative for this type test and the 10mm Ultrascopic was in use again tonight.

Lyrae now culminates by 11:00 in the evening. Tilting my head way back, I could hold the 5.5 magnitude test star under moderate aversion. So as the Moon continues to wane into the third quarter - and despite its position well above the horizon to the east, things be getting darker.

Just the way I've come to appreciate it...

Rings Anyone?

The Mars impression at left offers those who read these pages a sense of how little detail is possible on the planet as it continues distancing from our own. To be sure, image scale is off, as well as luminosity - but the impression of undefinable vagueness is well, unmistakable. In making the original drawing I realized that the south pole of the planet now nicely parallels with our own. Earlier in the apparition, that pole tended to "lean toward" earthwest. It now stands nearly vertical. Sky conditions were such that I could view the planet at 540X in blue and 360 in red. It was the fine view of the planet in blue that alerted me to the "rectitude" of the south pole. Meanwhile, that same view reinforced the idea of how intensely, electrically blue white "limb haze" is when present. Unlike last evening, darkish maria showed less contrast. Along with this was an inability to see anything but a few dark splotches with any certainty. The God of War probably continues to "stir things up" on the home front...

Finished drawing just before skydark. With the Moon well below the horizon, the Milky Way was quite dominant. Checking stars in Sagittarius returned contradictory results. Strangely, I could hold none greater than magnitude 4.0. - But I have yet to develop a systematic way of evaluating the southern sky for transparency. There is also the issue of seeing faintish stars against the Milky Way's lustre. Hopefully I'll have something together for the next observing session...

Of especial interest was whether any kind of aversion was able to reveal individual stars in 7.7 magnitude / 7 arc-minute M69. Last evening's hint of dozen's of stars just below the threshold at 180X was tanatalizing. Assuming a ULTM of 4.5,Argo holds 12.2 magnitude stars direct. Adding another 1.5 magnitudes to this, says that any stars scintillating across the cluster would shine at magnitude 13.7. To hold any of these stars with extreme aversion would mean I'd need to be able to see 12.7 magnitude stars direct - some 20 degrees above the southern horizon. And this, it turns out, is precisely what I saw. Maybe two dozen stars - nearly all outliers - sprinkled around the core region. So possibly the evening's transparency must have been closer to 5.0 than 4.5...

From M69 a short hop east brought me to 8.1 magnitude / 8 arc-minute sized M70. The cluster is easily seen in the 7X35mm finderscope. First impression: My, this baby is small! The light it sheds mostly concentrates in the starlike core and core region. Certainly that area could not have been more than 2 arc-minutes in diameter. The rest of the cluster is a hazy mantle and flares to almost all directions on eye move. This extends it out about 3 arc-minutes in every direction. (Although it flares most noticeably to the southeast and flattens to west.) The cluster terminates a "crooked line" of 8th magnitude stars from the northeast. Two 12th magnitude stars are seen due west at higher magnifications. At 70X the cluster looks unresolvable. But at 180X it begins to enliven as the eye sweeps over it. Maybe a half-dozen outliers can be seen on eye movement. Assuming an ability to hold stars down to magnitude 12.7, the brightest few members of this cluster must shine at around magnitude 14.2...

7.7 magnitude / 9 arc-minute globular M54 lies a couple degrees northeast of M70. Previously visited it while attempting to catch a view of asteroid Ceres. At that time an eyepiece impression was made. Fellow observer theAstronomer confirmed the location of the asteroid from the sketch. Once caught up with the observing plan, I'll do another and compare results. Even so I could tell that one "star" was missing from the scene. The asteroid has most definitely "eased on down the road".

M54 appears small, very blue, and intense. Like M70 - especially in the core and core region. Outside that area and extending out maybe 3 arc-minutes, is a vague luminous haze. This haze was completely missed during the earlier drawing. The cluster is the brightest study in its 70X, 40 arc-minute field of view. And takes up the root position of a largish right triangle (in association with a pair of 8th magnitude stars). Like M70, the cluster flares southeast and bears a large mantle. Unlike it, flattening shifts slightly south. Only the scintillation of a very few stars is possible at 180X. But by this time, the southern sky was brightened by an incipient moon.

A picture begins to emerge about all these globulars. There are more of them closer to the galactic core. They flare towards that core and flatten away from it. They lie at a variety of distances away from the earth - but possibly more uniformly from the core. Stellar population counts vary. Some are more concentrated, others sparse - all possess innumerable members. The visible flaring is probably the result of gravitation pull from the center of the galaxy stripping away member stars. Flattening opposes this on the far side of the cluster where combined tides of globular and galactic core "pack em in". Blueness, due to similarity of stellar ages and conditions of birth - along with generally uniform star masses. All of this is in the books - but you can see how those facts were arrived at - even through careful observation using a small telescope...

Witht the moon looming, I rushed through a few follow ups from last night's series. Amazingly NGC6603 was unambiguously present in the Small Sagittarius Star Cloud (M24). Exactly where I left it two nights ago - northeast of the double. Even more incredible was the view. There was the brightish linear streak of a half dozen unresolved stars to west. Looping around however, and unseen on the earlier occasion, was a torus of faint luminosity some 4 or 5 arc-minutes in diameter. The cluster looked quite annular. It was 180X on a slightly darker night that made the view possible. Bearing an average surface brightness of 14.2, NGC6603 is now the dimmest open cluster I've seen through 150mm Argo. Perhaps three stars could actually be seen at extreme aversion. On a decent night almost anything is possible...

However the sky giveth and it taketh away. Again nothing definitive about 9.4 mag / 10 arc-minute / 14.1 average surface brightness NGC6822 - "Barnard's Galaxy". Just one of several faint sheens out in the hinterlands northeast of the Sagittarian Teaspoon...

Of course I also had to take a peek at NGC6818. This planetary just begs for insanely high magnification (540X anyone?). It is definitely on my list for follow-up during the lunar first quarter.

The Moon was now well up into its third quarter. That taskmaster (fellow observer Cor Berrevoets) emailed me a map of the M57 region detailing a few choice stars for a secret project (shhhh). So I spent the next hour, Argo pointed straight up, groveling on hands and knees determining at what magnitude stars no longer show a visible 1st diffraction ring. (Where does he come up with this stuff anyway? And why can't he get a few decent skies of his own so HE can to do all the "nasty" field work ;>).

Well as it turned out stars of magnitude 7.0 show rings, those of magnitude 8 don't...

Argo's Favorite Globular Cluster

Despite a half-way decent sky (way down yonder above the southern treetops), Mars was definitely back to it's old tricks. Even though the full power and might of 540X could be turned on the planet, the return was neglibible. Through blue filter widespread limb haze extended from NPC to SPC. The south polar cap diminished but detectable. However, even bright hollows were remiss - not to mention any substantive semblance of dark maria.

360x and red filter showed, at best, vague darkenings proximate to polar regions. At 210x (in my estimation the lowest useful magnification given the planets sub-16 arc-second size), hints of Erythraeum and Niliacus Lacus perceptible. (With none of the presence seen earlier in the week.) The hope is that the planet holds a few final surprises in store before bowing out to the western sky...

In sweeping over to Antares, noticed that Mars now possibly lies further north than its rival. If there is one saving grace to the Incredible Shrinking Planet, it is that it now ascends in sky position... Dare I hope for a regional 7/10 stability sky, and an end to maria obscura before the planet passes the 10 arc-second threshold???

Views of Antares occured early on well before skydark. My main goal was to determine which filter best enhanced the presence of the secondary. With the sky approaching 4.0 ULTM, the blue filter revealed it best. Green darkened things too much, while red, though suprisingly effective in times past, gives an edge to the orange primary in terms of brightness. Something else of interest was the number of diffraction rings around the star (4) and the relative position of the secondary within those rings (near the 3rd). Also noticed that, despite seeing the airy disk of the primary, flameouts shot out past the 4th diffraction ring. So, the earlier assessment of conditions under which the companion may be viewed needs refinement. To see Antares little buddy requires the use of a filter whenever the stars spurious flashing exceeds the 4th diffraction ring. Should flashing remain contained within the third ring, a good chance exists of detecting the secondary without filter. In terms of seeing, 6/10 local stability is required to discern the secondary with a filter (blue before skydark, green later). Stability must approach 7/10 (if only briefly) to catch the star without.

Of course, I reserve the right to refine all this at a later date - as more experience with the pair accumulates. (May it be long in the coming!)

Since I'm on the theme of disparate doubles, let me add that Eta Draconis (under 7/10 seeing stability) is a surer split than Delta Cygnus under those same conditions. In fact, these three star pairs (Antares, Delta and Eta) make an excellent study in disparate double resolution. From my latitudes (~+37N), to get an unambiguous view of Antares companion (without filter), means I'll also see Delta-B and Eta-B. If Antares is only resolvable with a filter (like last night), Eta-B will show but Delta will be tough.

But this evening wasn't really about Mars or double stars - it was about globular clusters!

Argo loves 'em - and Argo especially loves M28. Why? Because this sweetheart gives a full sequence of "on the edge views" from 50X to 540x. More about this later...

Revisited M69. Under last evenings local 4.5ULTM & 5/10 stability conditions, this 11.6 average surface brightness cluster just begins to reveal a sprinkling of stars at 210x (under extreme aversion). Generally, bumping up magnification dis-improves the view. Low sky position is probably the culprit here.

Revisited M70. Under the same conditions, this 12.3 ASB cluster begins to sprinkle with scintillation at 360x and is bright enough to handle 540x - barely. Under a darker sky, 210X would probably provide the better view, BUT that extra magnification helps darken things enough to reveal a handful of stars on eye movement.

Revisited 12.1 magnitude M54: Due to its highly compressed and luminous core, this baby handles 540X just fine. It was only really possible to make out any scintillation at this super-high magnification.

Later in the evening, resumed ring testing. (This time in the region of The Great Hercules Cluster.) I must say, given its brightness and size, plus lofty sky position, M13 gives M22 a run for the gold when it comes to globulars. One reason: The sky is so very black and still overhead. The contrast in sharpness and transparency is breathtaking... During last nights tests it became pretty clear that the ability to see a stars diffraction ring is hinged to seeing an airy disk. Since airies begin revealing themselves at magnitude 7.5 (or so) in a 150mm scope, magnitude 7.5 is probably the upper limit for catching the first diffraction ring. Once a star is 5.5 magnitudes brighter than the direct view limiting telescopic magnitude (last night 12.8 - based on M57 region testing), the airy is quite obvious and first diffraction ring may be held direct.

Speaking of M22, had two neighbor kids over for a few minutes last evening. Showed them Mars, Mar's Rival, The Small Sagittarian Star Cloud, and The Great Cluster of Sagittarius. Now, you'd think Mars would steal the show - but that was not the case... The kids were more excited by M22 than anything else (with the possible exception of M24).

While it was still dark, made a quick run on Barnard's Galaxy - again this one is tough in a six inch, so nothing definitive on the usual vague (and ambiguous) brightening southeast of planetary NGC6818.

Two main studies were on the list for this evening - M24 and 28. Of course, I've visited with each previously. But tonight was their night for a closer look. Began with the globular cluster.

M28 is an easy finderscope locate west-southwest of M22. It's sky position - some 28 degrees at culmination - pushes it far enough north to break the 5/10 stability barrier that so often limits southerly studies. At 50X, the cluster showed a solid 6 arc-minutes of apparent size. Like most globulars, there was a bit of an axial skew - in this case, south-southeast to north-northwest. Unlike many dimmer cluster's, M28's 6.9 magnitude, 11 arc-minute sized globe showed the full panoply of globular features: Starlike core and bright core region ensconced in a bright halo surrounded by a dimmer halo of diaphanous luminosity. A close look at the cluster showed a vague - but not obvious flattening southwest. Eyemove revealed flaring to all directions - but especially southeast. The cluster is very blue and appears slightly rough at 50X. At 70X some scintillation is seen. 120X reveals a half-dozen stars under extreme aversion. 210X shows a dozen members under moderation. Two dozen at 360. M28's core integrity is such that it required very little effort to locate at 540X. But by this magnification there was nothing gained resolution-wise.

In contemplating M28, I became very mindful of this analogy: M28 is to M22 what M__ is to M13...

As mentioned Argo loves M28. Why? Argo is an adventurous telescope and likes discovering things. M28 offers layer after layer of interesting discovery. Through Argo, M28 is a full plate. All the virtues of Globular Clusterdom can be teased out of M28 - but it don't come easy...

Thus M28 is the perfect Globular Cluster Study for an optically correct 150mm telescope... In fact, the latest version of Seb Kalky (The Apparent Brightness Calculator on this website) says that a globular bearing M28's numbers is best viewed through a 184mm scope. But this is about to change... (I just love tweaking the software's parameters!)

As fine a study as M28 is, there is just no comparison between it and the Small Sagittarian Star Cloud. M24 is nothing less than a window into the heart of the Milky Way Galaxy. Turning your eye on this region is like peering through a portal into the "Holy of Holies". No one can look therein without being forever changed. In fact, it is impossble to even describe what can be seen there.

Suffice to say, and for me, the place to begin contemplating this region is with the lovely double star due west of the star clouds midline. At low power, and on a darkish night (Milky Way obvious to unaided vision) a six inch scope - such as Argo - will unambiguously show you the luminous glow of the beatific NGC6603 open cluster northeast of the double. Then after returning to the double, slew slowly west and take note of the double-arc of stars (located as far west as the double is east). Follow this with eye and mind to all the various other asterisms possible - plus the many unresolved glows and regions of obscuration.

Make a lifetime of it.

If it Ain't the Moon - It's the Clouds...

Just love it when I get to set everything up early and watch the tide of night roll in. Days can be so busy and demanding. But nights, that's when you can slow down and savor each moment. There is nothing like the descent of nocturna to give you a sense of sublime continuity with past, present, and future.

Add to this the quiet slew of the mount, the first kiss of radiance on the retina, and each moment becomes a fulfillment of inexhaustible promise and potential. Onward and upward! "Aye! Give me a fine scope and a star to guide her by!"

More ephemeral than the stars, the night and the sky may not be taken for granted. The finest of evenings can soon give way to the vagaries of weather. Water vapor ascends from the ocean and accumulates in the air. The air cools and gives birth to clouds. A distant high pressure system drives the clouds inland. The soft light of the stars yield to the thickening mist. In the eyepiece, dimmer stars wink out. And the crystal clarity of the field dissolves. The observer blinks ineffectually to clear the view. Then withdraws from the eyepiece to look up and see a thickening firmament. Still, patches of starlight remain. But the continuation of disciplined observation is wishful thinking. Yes, it is possible for the condition to be temporary. Clouds may move on. But odds are against it. Things tend to improve quickly or not at all.

Last night all of this came about just as I began contemplating a study that gives the appearance of a loose "globular" masquereding as an open cluster. It's hard to imagine that more stars could be packed into five square arc-minutes of apparent space without blending their light into a unity. However, Open Cluster M11 is only a partially constructed "globular". Three-quarters is missing! The process of star birth appears to have "rayed out" from a single bright 8th magnitude blue star. Its hundreds of eleven plus magnitude children distributed conically. Each star floats on the dark ocean of space within its own special "ring-pass-not". Certainly one of the most lovely treasures the Summer sky has to offer.

Earlier in the evening spent half an hour observing Mars at various magnifications. Although it is quite true that contrast improves between the darker maria and the brighter deserts at lower magnification, there is an obvious trade-off: Loss of detail. At this point in MarsQuest, the main concern is to get a definitve view of the planets surface features. Such a view necessitates higher magnifications. So each evening as skydark approach, I dwell on the planet at high magnification - hoping for the happy coincidence of a still terrestrial southern sky and a tranquil Martial equatorial region. Should such a moment arise, I am ready.

To be sure, high-powered views of Mars even now can be engaging. Were I content with the radiantly electric blues of NPC "limb haze", the subtle bulge of the South Polar Cap, and the soft gradient of the gibbous terminator (especially near the SPC) then MarsQuest would be complete and my aspirations fulfilled. But so far such ultimate hopes have been dashed - although on rare occasion they come tantalizingly close to fruition.

Typical Mars views are taken from 210 to 540X. On evenings when local seeing stability approaches 6/10, the blue filter gives excellent views of the brighter features at 540x. To monitor equatorial detail (and maria) the red filter is useful at 360x. Perhaps once a week I can use this scheme effectively. Most nights, the blue filter is screwed into the 15mm and red into the 24mm / barlow combinations. As such I'm limited to 360 and 210X respectively. Last night was such a night.

Since Antares is within easy slewing distance of the planet, I often drop by to monitor the star for its companion. In the several months of doing this I yet to see the 5.4 magnitude secondary as clearly as I did on the one occasion fellow SCAC member Dan's showed it to me through his Takahashi FS102 refractor. Despite the fact that 150mm Argo resolves tight doubles that the 102mm scope can't go near.

All of this leads to an important insight...

On any given night, there is a "best magnification" for seeing detail on the Red Planet. Just as there is a "best aperture" for resolving difficult double stars. Here's another example: Noted 19th century American astronomer E.E. Barnard discovered the large (10 arc-minute) faint, (9.4 magnitude) local group galaxy NGC6822 using a 4 inch refractor guidescope. Through the larger main scope, no sign of the galaxy was possible. Today experienced observers report seeing Barnard's Galaxy through 10X50mm binoculars, while I have yet to turn it up in 150mm Argo.

It was my hope last night to continue the quest for Barnard's galaxy. Due to the onset of clouds, that opportunity wasdelayed. The only question now remaining is whether it will first turn up through 150mm Argo at 52X or the 80mm Pup at 16...

Three studies on the year-long observing list were fully covered last night. First find was Open Cluster M18. M18 is found about a degree south-southwest of the Swan Nebula. To find this 6.9 magnitude 9 arc-minute group, I had to keep returning to the Swan repeatedly - just to make sure I was in the right place...

Bearing an average surface brightness of 11.3, cluster M18's brightest member's begin at about magnitude 8.5 and head south from there. At 50X, the cluster displayed perhaps 2 dozen members to magnitude 12. The group is quite oblate - perhaps 7X9 arc-minutes in extent oriented east-west. In general appearance the dozen or so brightest stars resemble a "running Hercules" - feet to west, arms to east. Most of the stars aggregate around the "Herculean" torso and to the north. These, plus the others in the asterism, are all brighter than the 10th magnitude. At lower magnification I got the distinct sense that the cluster is embedded right in the center of a "7-lobed star" of obscuration nebula. Outside the cluster, star counts dropped noticeably. In fact had this not been the case then it would have been a little tough to recognize M18 as an open cluster at all. Viewing the cluster at 180X brought out another dozen twelve plus magnitude stars. I suspect that this cluster has a long way to go before it assembles all its members. The huge disparity between brighter and dimmer populations, plus the relative absence of stars surrounding it, all speak to the idea of a cluster in the early stages of formation...

From M18, I ran with Hercules east a few degrees then dropped due south to locate Open Cluster M25. This group immediately revealed its "butterfly" shape and I realized it had turned up during a preliminary survey of Sagittarius earlier in the season. Due to it's large expanse, M25 has a dimmer average surface brightness (11.8) than M18. This might suggest it's brightest members should be similar in magnitude to M25. But in fact, they are distinctly brighter - perhaps as bright as magnitude 7. All told some 4 dozen stars between that and the 13th magnitudes were possible. (Dimmest visible only at 180x.) This particular "butterfly" spreads its wings over a 30x24 arc-minute region with an oriention along the north-south axis. Two rows of bright stars define its body. A small "number 9" shape group of 10th magnitude stars along the northern thorax is of especially note. Although it's unique chochlea shape was visible at lower magnifications, it was especially salient at 180x.

8.5 magnitude / 10 arc-minute NGC6645 lies almost due north (and slightly east) of M25. Due to its 13.2 magnitude average surface brightness, this relatively expansive group of 2 dozen stars did not exactly wave a flag and shout "Here I am". Add to this the fact that we are talking about a pretty star-studded region of the sky and you can understand why I used every trick of slew and view to unambiguously settle on the cluster.

Unlike other 13 plus magnitude ASB groups, 6645 showed a remarkable number of stars. The brightest seemed to begin at about magnitude 10.5. And took the general shape of a "six-pointed star". The faint sheen of dimmer components could be seen at low powers. 180X however, failed to resolve the nebulosity. What 180X did bring out was a fine, faint 5 arc-second triple whose three components formed an isoceles triangle. The brightest member could not have exceeded magnitude 11. Dimmest, magnitude 12.5. This third component was not even suspected at 50X. Only the brighter pair caught my notice. The multiple is visible within the southwest "ray" of the cluster.

From NGC6645, a 6 degree slew due north brought Alpha Scuti in the finderfield. Another three degrees north-northeast lures in Beta. From Beta it's easy enough to locate "The Wild Duck Cluster" to the southeast. Initially the sky was dark and transparent. The cluster was rich in star density and population. I enjoyed it while it lasted.

It will be there again tonight. Though clouds may stand between us. It will be there...

Help From an Unexpected Quarter...

As most readers are aware, I've spent a good deal of early evening observing time doting over the difficult Antares resolve (and planet Mars).

This evening an interesting assist came forward from an unexpected quarter. Well before dark I could see clouds piling up to the south. It was clear to me that the evening's deepsky study plan was in jeopardy. The only question was whether the clouds would roll in before or after skydark.

And as it turned out, the clouds won the race. And in a way, so did I.

These particular clouds were translucent - at least initially. It would have been a bit much to ask for them to remain uniformly so - and from a certain perspective the fact that they weren't was advantageous. For, as the clouds rolled in, the spurious image of Antares began to shrink and its associated "tongues of flame" abated.

Of course the veiling clouds also diminished the brightness of the companion - just as it quashed that of it's brighter confrere. But there was the occasional point of balance, and the dim companion could be seen unambiguously clear of Antares airy disk.

Now can you guess how many diffraction rings were visible as this optimizing point occured?

If you guessed "one", you are correct. For whenever the primary showed more than this number, it also flashed and in so doing obscured the secondary (though it still could be seen - but with difficulty). There was also something else of real interest. As clouds obscured the primary, I could see it's airy disk shrink with the reduced luminosity.

This observation was done at 210X. At that magnification, the secondary stood well clear of the primary. One test was to determine position angle. During brief periods of optimal visibility, I noted the pairs drift across the sky. The secondary lay almost perfectly west of the primary. (I was hard-pressed to determine if more north or south - and if I had to guess which would say south-north or maybe north-south? ;>).

Since the observation was done sans filtration I could also guage the secondary's color - greenish blue.

At no time did the secondary show an airy disk. Simply because whenever I caught sight of it, it was simply too dimmed out by the intervening clouds that paradozically made it visible at all.

Now it just so happens that all this follows a series of observations done earlier this week in which fello observer Cor and I determined that the dimmest star to show a definite first diffraction ring approximates magnitude 7.5. As such that star is roughly 5.0 to 5.5 magnitudes brighter than the limiting telescopic magnitude of our scopes (considering both magnification and conditions).

Antares companion is magnitude 5.4 and the primary, magnitude 1.3. So a 4.1 magnitude delta exists between them. Assuming that Antares A diminished to magnitude 5.0, then the secondary would be seen as magnitude 9.1.

Evaluating such a pair (5.0/9.1 2.4 arc-seconds separation) using the Double Star Calculator indicates that seeing conditions must still be pretty good (7/10) to make out the companion - so there really is no boon to be had by simply dimming Antares to the point where it approximates magnitude 4.0. (After all I did see a decently concentric 1st diffraction ring.)

However, I can say that tonight's view of Antares - aided and abetted by a somehwat translucent cloud cover - was the best yet through 150mm Argo.

One final note. As mentioned, I viewed Mars furing this period. There was no question that the limb sharpened up considerably in the presence of the clouds. One might think this was due to a "steadying" of the atmosphere - but that was not my impression. The sense was that the clouds "absorbed" randomized "planetary ghosts" and reflections. This allowed the "true Mars" to unequivocably present to the eye. So much of what is seen as "blur" in the planets image may come down to secondary and tertiary images of the planet confusing the eye.

This is something I had never thought of before...

Unlike Antares though, there never was an instant when the Red Planet's features coelesced before my amazed perception. That event must await another night and probably another apparition.

Oh Yes, Where Was I?

Turned up Mars by finderscope well before skydark. Decided to see if the Kellner's that came with the Pup would make useful planetary eyepieces. Tried this before on Jupiter month's ago. Results were not conclusive. Views were about the same as the Ultrascopics - but a little "ghosty". Field not quite as flat but perhaps brighter. Why not play with them again?

Had previously removed the shorty barlow negative lens from it's tube. The idea was to use that tube to achieve focus during "straight through" viewing. To protect the barlow lens, threaded it into the 10mm kellner. Got the idea to try the Kellner with barlow lens installed. Knew it would work, but wasn't sure if the combination would come to focus. Also wasn't sure how much of a boost would come from using a negative lens that close to the eyepiece.

As it turned out, the combination came to focus - with and without the diagonal. Did some transit timing tests to determine what the gain was. Found that Mars tracked across the field about one and a third times faster with the barlow threaded into the eyepiece barrel. So now I can basically extend my eyepiece collection all the way up to 240X - without having to use the Ultrascopic barlow. Only downside seems to be off-axis correction. Not quite as sharp near the field stop as without it.

So of course, I'm now in optics mode. With a resonably stable southern sky - and the 10mm Kellner with one and a third barlow in place started twisting the thumbscrews on the secondary. This alone didn't cut it. Intra-and extra focal concentricity did not match position in the eyepiece field. The inevitable escalation occurred. I got out the allen keys to tweak the primary as well.

By the time I'm done, flaring around Antares diminished visibly and the blue-green secondary can be seen distinctly separate from the primary's "tongues of flame". Meanwhile, Mars limb looks quite sharp. The scope is tuned and sky is relatively still. But Ares doesn't want to come out and play.

By this time its skydark and I've got a date to fly with the waterfowl - M11!

The sky is quite dark. 5.3 magnitude SAO105168 can just be held direct northwest of Gamma Aquilae. M11 is an easy locate in the finder. The first view staggering at 70X. Dozens of dozens of tiny luminous gems seen against an almost jet-black sky. It's so dark that the Duck looks more like an "Angel". This as two dim "wings" of stars sprout south and east. The cluster's normal "conical" shape is almost lost. The cluster becomes oblate by extending out by some 10 by 12 arc-minutes north and south. At the center of this ovoid is a single blue 8th magnitude star. This is the jewel in the midst of the cluster's lotus. All other stars appear 10th magnitude and dimmer. Surely the core star is the supermassive progenitor of all the others. Driving cosmic gas and dust toward incandescence with its fiery radiation pressure.

I suspect the stellar birthing process is incomplete. Several dark obscuring bars can be seen running laterally between the central fire and a pair of equally bright eight magnitude field stars. (This widish pair lies on the cluster perimeter south of the core.) At 180X, numerous obscuration regions can be seen - even (and especially) within the bright conical region that gives the cluster its familiar name: "The Wild Duck Cluster".

From M11 I dropped southeast to make another run at locating "Barnard's Galaxy". Easily located the small, tenth magnitude planetary NGC6818. Noticed that galaxy NGC6822 lay slightly east of and equidistant from the planetary and a sixth magnitude star. So split the difference and slewed slightly east at 50x. Kept noticing a vague 4 X 8 arc-minute, east-west oriented region of exceedingly low surface brightness between (and west of) a pair of twelth magnitude stars. No matter how many times I repeated this maneuver, ended up at the same place. Put a towel over my head and did it again. Same place - and even noted a bit of brightening toward the center of the "sheen".

Nothing definitive mind you...

From the 6818 region shot north to Delta Aquili, then west to Theta Serpens. Wended west-northwest between a pair of north-south oriented sixth magnitude stars to a "star cloudy" looking finderscope region - IC4756.

At 50X, the cluster completely spilled outside the 1 degree field of view. Initially I wasn't sure if I was in a cluster or an isolated Milky Way star cloud. Then noticed how star density concentrated toward the center. This convinced me that I was perusing an actual cluster. Large and bright, IC4756 easily reveals one hundred plus members ranging from magnitude 6 to 13. As mentioned, a 20 arc-minute region could clearly be identified as its core. Interestingly, in examining the core, I realized that its many stars liked to aggregate into small groups. Many circlets, arcs, "Y's" and other recognizable shapes were possible. Numerous dark bands wended their way between the groups. Got the impression the cluster was trying to communicate using some kind of obscure symbolic language...

Spent the next hour or so fruitlessly searching for planetary NGC6790 in Aquila. Used my best methods to isolate its location. Swept the region dozens of times. Found several faint nebulosities - but none bright enough to be considered magnitude 10.5. Perhaps this value is wrong. Certainly the sky was stable enough to enable me to distinguish between a star and a 10 arc-second diameter planetary. And I had already done this earlier in the evening in looking for Barnard's Galaxy.

The search was not futile however. During one sweep - well west of my target - came across something that looked suspiciously cometlike. There was no corresponding reference in my atlas so, after nailing down its location as precisely as possible (3 degrees southwest of Delta Aquili) checked it against software on the PC. Turned out to be 9.1 magnitude globular cluster NGC6760.

At 70X NGC6760 showed a starlike core (under moderate aversion) immersed in a roundish central brightening and dim halo. Higher magnification showed several 13th magnitude stars on the perimeter of the cluster (probably field stars). At 180x the brightest part of the core shifted west, while a sense of flattening was possible south and flaring north. The cluster is located about 12 arc-minutes east of an eighth magnitude white star.

Made a few more desultory sweeps for the planetary then relocated Argo to the north observing station. Got a nice split of the Double Double. Easily held the 12.8 magnitude test star near the ring at 180X. Found that the 13 magnitude star was a bit soft - but direct and almost held the 13.4 magnitude test star.

Turned Argo on Delta Cygni. Instantly saw a very obvious brightening southwest of the secondary. Dismissed it as an aberration and proceeded to recheck Argo's collimation. Made a few small adjustments to better coordinate inside and ouside focus. Then bingo!. Started seeing the loveliest little pale blue airy disk conceivable. Right there within two and half arc-seconds of that overly flashy 2.8 magnitude primary - Delta. Decided to try out the kellner/ shorty thread in combination (140X). No sweat! How about 120X? Elongated. A Definitive View.

Since I had earlier caught Antares-B, and now Delta-B, it made sense to complete the hat-trick with Eta Draconis. As it turned out, Eta-B was a bit of a challenge this evening - but could be definitively seen. Keep in mind that by this time Eta was well down to the northwest and not in the best of sky positions...

As I packed Argo away, noticed a much diminished Moon rising to the west. Midnight, and the Moon rising. Wasn't even tempted to setup Argo. The evening was full enough as it was.

Fire in the Sky

Last night was Fun! (But aren't all the SCAC star parties Fun! - except maybe the one's where I'm the only member to turn up - and even those are fun.)

But in addition to being fun, last night's party was special. For last night the Perseids came to town. And boy, did they put on a show! Every ten or fifteen minutes you'd look up and there - streaking across the sky, angling south from the direction of Cassiopeia and distant Perseus - would be a thin shaft of light. A light whose ephemeral existence was briefly followed by the faint, ghostly glow not unlike a dissipating atmospheric comet.

Or, if like myself, your head was threaded into the barrel of an eyepiece, every fifteen minutes someone - from among the group of two dozen observers present - would shout "Did you see that one, it was incredible!"

And coming in, I thought I was immune to meteor fever. Impossible. It was pandemic!

So as the Perseid's took their shower, some seriously enjoyable observing was also going on. Fellow SCAC member Dan and I set up as the "optical fervor duo" west of the dobs and east of the SCTs. And with Argo all collimated, I was ready to put both scopes through their paces. Dan also had an agenda - working his way through a Messier study (something he's done before on other scopes) - but not using the Tak. Meanwhile, a nice couple turned up (Peter and Niya?). The three of us toured the Milky Way and beyond through Argo.

This particular tour was also special - and one I will always remember. Dan loaned me his "spare" Nagler (16mm) eyepiece for the duration. And Peter, Niya and I were given incomparable 80 degree views of all the glories of the Summer Night Sky. With few exceptions this became my "eyepiece of choice" through the evening...

Dan had setup before I arrived. Everything was in place, but with one huge exception - the power connector to the Tak's drive system open circuited. The Tak would be going unplugged for the evening. Complicating this is the fact that the Tak's mount lacks manual slow motion controls - so slewing was not unlike pushing around a big dob. Very un-nice at 250x. Meanwhile, I arrived with one huge bother - Argo overheated and took an hour to stabilize. Thus, from a site with excellent southern sky stability, views of Mars and Antares were a wash. In fact, tube currents were so bad initially that son Eric and I could see the Great Symbol of the Klingon Empire in the 1.3 magnitude star's spurious image.

By skydark though, Argo had settled down. Peter and Niya became my constant companions as we started way down south near the scorpion's tail and headed northeast. Here was my chance to prove everything learned about this region over the last month (while persuing my year-long observing plan). Lagoon, Trifid, and Swan (Omega) Nebulae. "Strawberry", Butterfly, "Dragonfly" and incomparable Wild Duck clusters. Sagittarian Star Cloud with gossamer torus of open cluster NGC6603. Planetaries M57 and NGC6818. Globular Clusters!: M4, 80, 62, 19, 22, 13, 30. And even a few galaxies: M51 (earlier) and M31 & 32 (later on).

While viewing the Trifid, turned Dan on to the sweet little double star embroiled in the western lobe of Trifid nebulosity. Then introduced him to the mysteries of the faint 11th magnitude ~3 arc-second member that makes the pair a multiple. In fact, the fine optics and excellent contrast of the 102mm refractor was able to reveal the 11th magnitude star (right on the limits of averted vision at 250x). Meanwhile through 150mm Argo, the star was a tad easier (but could not be held direct).

We also turned Dan's Tak on Delta Cygni - twice. Earlier with Delta having just entered the skies middle third, the view was pretty much the way Argo usually sees it - flashing spurious primary with hints of brightening to southwest. Later, with Delta almost directly overhead, Argo and the Tak cleanly resolved the pair. Beautiful airy disks - both primary and secondary. Dark of space between. This speaks loudly about the quality of the sky, and the excellence of the optics of both scopes.

After a while Peter and Niya took their leave and I began paralleling Dan as he tracked down south-sky messiers. The bulk of his studies were globulars. So for the next hour, Dan would find a cluster - say M19. And I would find the same cluster. We'd compare views - both at about 120X using Naglers. (His 7mm, mine the 16mm.) Every globular viewed showed at least a few resolved star (except the impenetrable M80). In their sum, the following conclusions could be drawn: 150mm Argo gave visibly better resolution, and slightly brighter images. While the 102mm Tak gave a slightly darker, more contrasty background sky. To be sure, a fine 4 inch refractor is an excellent instrument for viewing Messier classed DSOs. (And as learned later - the brighter planetaries.)

Once Dan finished his observing list (a first for him at an SCAC star party), I went after my latest challenge - planetary NGC6790 in Aquila. The way I figure it, the wide-field, high magnification Nagler would make it a cinch to turn this one up. But in fact, after about fifteen minutes, I quit unsuccessfully. Meanwhile, Dan was busy tracking down a larger, brighter planetary - NGC6572 - in Ophiuchus. Now planetaries are tough, and not easily recognized. Since I'd found this one earlier in the month it was a cinch for me to pick it out again. So, breaking off from my efforts, I worked with Dan to locate it. Happy to have done so - the Tak gave a very fine rendition of this beautiful robbin's egg blue wonder. Like Messier's, the brighter planetaries are just the ticket for an optically-correct four inch scopes.

By 1:00am, most of the evenong's gathering had dispersed. Dan, I and a fellow observer (wielding a 10 inch Discovery Dob) were wrapping up as well. The sky had become quite gauzy with an incipient Moon. Peter and Niya had returned earlier for more views. We turned the scopes on M31. Dan dropped way down in magnification and managed to fit the visible portion of the galaxy into a 25X field of view. Now this is M31 as it should be seen. All in one field and packed with contrast. Argo can't touch this. This is the special perogative of the short focal length refractor. The 80mm Pup is going to love M31!

By 1:45 we had packed up. It was wind-down time. I made some bold statements regarding scopes: "Ideal refractor: 140mm, F7 apochromatic." "Ideal Maksutov Cassegrain: 175mm, F12". "Ideal SCT: 250mm, F10". "Ideal Dob 300mm, F5."

Dan has more experience with a variety of scopes than I have. He's not sure there is a "sweet spot" for apertures and scope types. Our friend with the 10" Discovery Dob was content to listen. Of course, I explained the rationale behind each choice. Yes, a 125mm refractor is probably the ideal lunar-planetary scope - as many suggest, but personally I'd want the extra girth for deepsky. And yes, more aperture would be great on the Mak, but cool down can became a serious issue - one that Mak-ufacturers are trying hard to offset. And yes, an 8 inch SCT is more portable - but why get one when you can get an equally portable 7" Mak, likely to possess superior optical quality. And yes, the bigger the Dob the better, but a 12.5 holds its own pretty well against larger apertures, is more easily transported, and can be had with better optics for significantly less.

Just about this point in the conversation, the whole sky and earth beneath our feet lit up. Directly overhead, a bolide soundlessly exploded miles above us. It's huge vapor trail remained luminous for the next five to ten seconds - then slowly faded away.

There was no more to be said, except "Did you see that one? It was incredible!".

A Vague Sense of Frustration

The evening started out fine. Had Argo and the Pup arranged side by side on the north deck early in the evening. Mars could be found through a dusky sky through both finderscopes. Image scale just too low for the Pup. Argo suffered the usual early evening tube currents. Spent some time following Antares through the Pup while Argo stabilized. Yes, the were even a few microseconds where I could almost convince myself that I caught the star's 5.4 magnitude green companion through the 80mm Pup. Within a half hour, Argo had settled down. Mars gave a superlative view of whatever at 360X.

Given he superb edge focus achieved last night, the sketch at left should show the entire Mare Erythreum complex above and Acidalium complex below (north). The view should have been simply superb. Dark maria continents arrayed right along the central meridium. Bright Chryse in their midst. But instead last night, Mars closed all the curtains. Limb haze, polar caps, eveything in abeyance - but what an incredibly sharp edge to the planet. And how lovely the luminosity gradient along the gibbous terminator.

Despite the fine view of Mars limb (seeing stability probably 6/10 regionally), Antares remained a puzzle. But I really didn't dote over it - not with Argo anyway...

Frankly all evening I was feeling rushed. Two Summer deepsky studies from the yearlong observing list have eluded me. I was anxious to continue the quest - and the Mars sketch dragged on into skydark due to delays in stabilizing Argo. (Man, it got cold quick last night!)

Had no rouble tracking down the Barnard's Galaxy region last night with the Pup. (Sure, there were issues with the poorly designed EQ-3 mount it rides on - but what the heh - it only cost $75...) I knew as soon as I looked through the 16X eyepeice that I was not going to definitively catch 14.2 ASB NGC6822. The sky was just too bright. So I switched over to the 15mm (for 27X) and resumed my sweep. Nothing more than "imaginosity". Low powers are great for concentrating light - all kinds of light. As it was, the dimmest star visible to me was magnitude 4.6 SAO162518. The milky way itself was quite bright - lanes easily seen dividing the stream of stars like some dark sand bar in the Mississippi River...

Since I had the Pup out, thought it might be nice to go with the Milky Way flow. Started at the Lagoon - very contrasty at 27x - dark bars between the three cloudy lobes, Strawberry cluster - yum yum. Lagoon, lower surface brightness but still obvious. Engulfed double just resolvable at 27x. Small Sagittarian Star Cloud, rich and diversely textured - even the faint torus of NGC6603! Butterfly cluster clean - although the cochlea was hard to make out at this low magnification. Even faint NGC6645 showed a few stars. Swan Nebula - graceful and distinct. Then Eagle Nebula in full frontal display! Of course M11 was fully resolved, hundreds of 11th magnitude lights. I tell you, the Pup was made for the Summer Night Sky.

But now my journey had carried me north to Aquila - and minute planetary NGC6790. Had done some research on the internet. One poster identified the planetary as being located 1 degree, 45 arc-minutes south of third magnitude Delta Aquilae. I swept to the region. One 45 arc-minute field of view. Two 45 arc-minute fields of view. Here I find - two 8th magnitude stars. Then another third of the field. Strangely barren field, all stars dimmer than magnitude 11 - nothing bright enough to be a 5 arc-second, 10.5 magnitude planetary.

So I head west to a much livelier field with maybe eight or nine 9 plus magnitude stars shaped like a Lear Jet seen from above. Cockpit to northwest, tail southeast. The entire asterism took up about 30 arc-minutes of the sky.

And right where the pilot ought to sit, two stars. One of the 10th and the other approaching the 13th magnitudes. The 10 mag lay to the east and looked a bit peculiar. The 13th mag some 15 arc-seconds distant required a wee bit of aversion to fix in the eye. The brighter "cockpit star" was about .8 magnitudes dimmer than another star taking up the Lear Jets nose. The cockpit star appeared vaguely "larger" - but not definitively so. Even at 180X it was not "larger enough" for celebration. So one test - magnification - was inconclusive...

Pulled out the OIII filter. Figured the cockpit star would appear brighter than the nose star - if indeed the cockpit star was the planetary - with the filter applied. But, at best, Star Cockpit only seemed to get about as bright as Star Nose. Again inconclusive.

Made an effort to run the magnification up - but despite the fine view of Mars earlier - seeing stability was having none of it...

So that's where I stand. Mars needs to cut some slack. Barnard's needs a darker sky. NGC6790 wants for some serious atmospheric stability. And I'm left feeling vaguely frustrated...

Galaxy Quest Continues

Like last evening, had both scopes setup and ready for action well before skydark. South-sky seeing stability was quite poor (4/10) and remained so throughout the evening. Mars, though not a blurry blob, was a smear and would not come to focus in either scope. Despite early setup, Argo never really stabilized while Antares was in decent sky position. The Pup however was seeing things differently. (Refractors - especially small bore jobs like the 80mm - tend to come to thermal stability quickly. They also are less subject to atmospheric turbulence.)

To be sure, the view through the Pup was less than perfect. Three (maybe four) diffraction rings could be seen northeast of the stars spurious disk. Diffraction rings hardly visible to the southwest. Clearly something was wrong...

What was obviously wrong was the "wobbly" way the ultrascopic barlow sat in the scope. The outside diameter of the barlow is simply too small for the inside diameter of the focuser. Tried shimming the barlow. This helped - but was sadly unprofessional... Hit on the idea of using the shorty barlow barrel as an adapter to the ultrascopic. Found this worked quite satisfactorally. Even with a stable barlow in place, the ring shear persisted. So now it was time to check the object lens cell and see if there was anyway to adjust the collimation.

Removed the dew cap and three screws fastening the object glass cell. No adjustments visible. On a whim, decided to rotate the cell by 120 degrees. The result: Significantly improved concentricity of Antares diffraction ring presentation. So good in fact that it is now pretty easy for me to believe that I can make out the 5.4 magnitude companion dancing just outside the spurious flashing image of the 1.3 magnitude primary...

Later (much) turned the Pup on Delta Cygni. Overhead stability (for the Pup) about 7/10. The primaries spurious image merged with - but did not exceed the 1st diffraction ring. To the southwest (and using slightly averted vision at 150X) could make out the 6.4 magnitude companion. Very difficult - but possible. Hope to get a definitive view on an 8/10 stability night.

At 6/10 stability, Delta revealed nothing but the faintest hint of a companion to Argo. In fact, Argo had trouble distinguishing the more disparate Epsilon-1 pair of the Double Double. One reason - high, thin, and variable clouds. This caused considerable glow between components.

Between views of Antares and Delta Cygni, spent the bulk of the time tracking down 14.2 ASB Barnard's Galaxy. Had printed some charts off the web (using SIMBAD). Unfortunately, the charts don't give a good sense of field star relative brightness. So despite seeing a very dim hazy glow some 45 arc-minutes north and slightly west of a pair of a 6th mag field stars (through the Pup at 27X), really couldn't nail this one down.

Usually don't hang around waiting for the sky to darken enough to quest for Barnards. Before skydark, tend to start way south at the Lagoon Nebulae and work my way north. Along the way, I confirmed everything in the previous report. The Pup can (just barely) resolve The Wild Duck Cluster (M11) at 27x. And faint open cluster NGC6645 can be seen - even a few bright stars made out with averted vision...

Made no effort to go after small planetary NGC6790 in Aquila. (For obvious reasons.)

Maybe, just maybe, this evening I'll be able to track down these two challenges and get on with the rest of my observing life...

But if not, can always remind myself of the dozens of attempts made to definitively view NGC6888 (Crescent Nebula in Cygnus) before everything came together and my observing soul was satisfied...

Takes a Darker Night

Sporadic clouds graced the sky in long streamers - especially overhead and northwest. As eventide settled in, winds picked up, blew the clouds away and pulled the rug out from under atmospheric stability. As the evening progressed, there really was no improvement (for Argo anyway) - despite the fact that the wind abated.

But for the 80mm Pup, things weren't quite so bad. Both pairs of the Double Double solvable. Delta Cygni's 6.4 magnitude companion could be caught with mild aversion south and west. Despite the fact that some collimation method is neededto really align the object glass...

Argo was able to resolve the closely matched Epsilon-2 pair - but not more disparate Epsilon-1. This kind of performance usually means Argo is looking through 5/10 stability skies. And this suggests that efforts to track down small planetary NGC6790 would prove futile - at least using the usual method of comparing star-disk sizes...

My alternative was to accurately align Argo to the pole, sweep due south of Delta Aquilae one degree and forty-five minutes and begin looking for asterisms. A useful reference for this approach was an eyepiece impression found on the web. The impression showed a 150+X 6" Newtonian view of a 15 arc-minute line of three stars oriented (more or less) east-west. Each star roughly of the tenth magnitude and the planetary taking up the middle position. The sketch showed that the easternmost star had two 11+ magnitude distant comes taking up the 7 o'clock position around it.

No definitive asterism was found to map against it. However, in comparing that drawing to a printout of the region using web-based SIMBAD, it's clear to me that the observer had actually located the nebula for the sketch - quite an accomplishment (in my estimation). Now I have to track down another possibility: It's entirely possible that another report found on the web erred in saying the nebulae is one degree, forty-five minutes south of Delta Aquilae. And to work this one out I need to do a bit of homework. (Which follows.)

*************************************************************
NOTE: Homework:

Delta is located at: RA, Dec: 19h 25m 29.9s,3d 06m 53s N (E2000)
NGC6790 is at:       RA, Dec: 19h 23m 16.0s,1d 31m 10s N
The difference is:                 2m 13.9s,1d 35m 43s

2 minutes in time is roughly 30 arc-minutes in space (at or near the celestial equator) Ergo Argo: Look 1 degree 30 minutes south and 30 arc-minutes west of Delta.
*************************************************************

But last night I attempted a systematic comparison of all stars in the aforementioned field using the 25mm Ultrascopic eyepiece (with OIII filter) and the 25mm Kellner (without). Spent more than an hour as Aquilae drifted west to culmination and beyond... Found one star in particular, that looked promising - but it didn't show enough delta between filtered and non filtered views. (Although it had the telltale "robbins-egg blue green" color...)

But all this happened much later in the evening...

Before skydark, got an eyeful of blurred out Mars (bright NPC limb haze though!) and "flashy" Antares at 240X. Had the Pup setup in the north observing station (with Argo to the south). As the sky darkened, shuttled back and forth between the two scopes. Wanted to get a sense of overhead conditions with the Pup. And determine whether the 80mm Pup could give a "definitive" view of Delta Cygni's 6.4 magnitude companion. (Pretty much the same view as the previous night - averted vision during stabler moments while Delta Cygni drifted across the field of view at 180x.)

At its darkest the sky showed overhead stars down to magnitude 5.5 unaided. The Pup revealed the 12.8 magnitude star near the "Chalice of the Ring" - with full aversion. Could make out both the 13.1 and 13.4 magnitude test stars on eye movement - all at 180X. (Lots of glass here by the way, 3 elements in the Ultrascopic barlow, 2 in the shorty "thread in" barlow, 4 in the 9mm Plossl, plus the doublet that sets everything into motion. Add a rather cheaply made diagonal - and guess how deep a near-perfect 80mm APO would go under these circumstances!)

Meanwhile a similar test done using Argo showed the 12.8 mag star direct and the 14.6 mag star flanking the Ring on eye movement. (Now consider Argo's accoutrements: One correction lens, one primary convex spherical mirror, one concave secondary mirror, one slightly better mirrored diagonal, and one five element Ultrascopic eyepiece. Glass is better than mirrors!)

And oh yes by the way, there are few finer studies in the sky to host telescopic limiting magnitude tests...

Once the sky got truly dark, resumed Barnard's Galaxy Quest. This time using Argo at the lowest available magnification (52x). First off, could tell it was a darker night than that of the last several (unsuccessful) ventures. 4.6 magnitude SAO 162518 could easily be held direct. Estimated the southern sky in this region to approach 5.0 - at its darkest.

From SAO 162518 (just north of Rho-1 Sagittarii) slewed due west to a small group of finderscope stars (5.5 magnitude SAO 162883, 5.1 SAO 162915 and 5.5 SAO 162931). These last two separate by about 45 arc-minutes and point north to the vacinity of Barnard's Galaxy. Between SAO 162931 and the Galaxy is an asterism of about a dozen 7 and 8th magnitude stars shaped like a distorted "Sagittarius". The asterism is roughly 15 arc-minutes north of the galaxy...

The only hints of NGC6822 presence was the diffuse eye movement 4 by 8 arc-minute north-south oriented sheen encompassing a 2 arc-minute averted vision "brightening" of a core. Several 12 plus magnitude stars could be seen arrayed around it. Not what you'd call a "good 150mm study".

But not a bad 150mm find however...

So that was my evening. When you're dealing with large low surface brightness studies, you need all the sky transparency you can get. And just a couple points more made all the difference.

Mars is Back! For How Long?

And this evening's first big surprise was... Mars is back! That's right, ladies and gentlemen. The long wait has been rewarded. Syrtis Major Earthwest. Erythraeum-Acidalium Eartheast. Sinus Sabaeus arching along the south central meridian. Too bad seeing wasn't better (5/10) early on. Limited me to 240X and averted vision for what passed as a definitive view. But quite unmistakably, there is a break in the action on The Red Planet. Care to bet how long it lasts?

But this was just the first surprise for the evening. Turned Argo on 5th magnitude twin star Gamma Coronae Australis. Numbers available at the time showed both members magnitude 5.0 - separation 2 arc-seconds. At some 15 degrees above the south hotizon - didn't think there was a snowball's chance of resolution. Especially after seeing the marginal view of Mars some twice that distance above the horizon. Located Gamma at 70X. Strangely, the pair appeared ever so slightly elongated - hmmm. Switched to 120x: Was that a slight hourglass pinch at the waist? Now 180X: Watched in amazement as the pair went through its dance: Dissolve into a rainbow arc of colors. Pull together into an out of focus blur. Then a flashing radiant orb, finally two golden Suns, separated by an obvious line of separation and oriented roughly southeast to northwest. Then reversed sequence: Split, flash, blur, dissolve, and start all over again.

NOTE: Latest line on this pair: HJ 5084 Magnitude: 5.01/ 5.05 1999: 1.3"/ 62° Spectral Class: F8V F8VData (research courtesy Cor Berrevoets).

Well, you'd think that first a maria ex obscura Mars followed by a 1.3 arc-second split less than a fists height above the horizon would be enough! But no, I had to go and observe brightish (7.0 magnitude), HUGE (19 arc-minute) globular cluster M55 - just as the southern sky from Backyard Boulder Creek was showing real promise!

Hello! This thing is very open, possesses a multitude of fine, easily resolved 11h and 12th magnitude stars spread somewhat oblately over some 12 arc-minutes of apparent space. At 70x, several dozen stars readily seen with the least bit of aversion - many direct. At 120X, maybe seventy-five to one hundred cluster members discerned - with dozens direct. By 180X, the group took up two thirds of the 17 arc-minute field of view. (Thought 120X gave the best view though - due to M55's position some twenty degrees above the south horizon.)

Had little trouble characterizing the shape of the cluster. One thing noticed was a group of four brightish outlying stars framing it (inside a parallelogram). Three of the four stars were visibly brighter than the fourth. The effect became one of a triangle with apex to west. Within the triangle many cluster stars could be seen - giving the appearance of a sunfish with a body much taller than long. Add to this the three framing bright stars and voila - you get an "Angelfish". (The western star marking the nose while the other two its dorsal and abdominal fins.)

Had no trouble finding this cluster - easy finderscope locate. While sweeping the sky near the cluster (at 70x) caught faint sight of a large (5 arc-minute) faint glow some 20 arc-minutes east and slightly south. Can't find anything on my free Orion software charts that corresponds - but the sighting was relatively unambiguous. Some research needed here...

So by this time (10:30-ish), had had a "late-hit" view of Mars, split a close double star near the horizon, and resolved nearly one hundred 12 plus magnitude stars within a large, bright globular cluster. Shouldn' I just quit? (Too much sheer pleasure for one night already!)

Well, there remained the matter of that tiny, tenth magnitude planetary nebula hanging out in the rich star fields of Milky Way Aquila...

Slew to Delta Aquilae. Sweep one and a half degrees south to a widish eighth-magnitude matched pair. Shift half a degree due west. Find a forty-five arc-minute field of a dozen ninth and tenth magnitude stars. Begin looking for anything suspicious. Oh yes, that one sure looks odd. Bright, robbins-egg blue-green, type odd. Pop in OIII filter. It stays bright - everything else dims. Remove the filter - everything gets equally bright. Bingo!

No way to tell this was the planetary based on size! Sure the thing spreads out over six or seven arc-seconds in a Hubble image. But, at best, 2 arc-seconds of NGC6790 possible through an earth-bound 150mm scope visually monitored. Switched to 180X, 8/10 seeing. Yes, definite planetary disk with a small bright "dimple" of starlight at core. - Probably not the star (that's magnitude 14.7) but definitely a region of greater nebular excitation. Avert the vision, maybe a dim outer halo possible. But that's it. Much brighter - and smaller than expected - but little more. Small planetary challenge fulfilled!

So now, I get to play. Overhead stars to magniude 5.5 direct. (Test star in Lyrae just possible - almost as a star point.) Pup shows me 12.8 star on aversion near the Ring. Delta Cygni displays a perfect airy disk with a single (slightly displaced) diffraction ring almost completely (but dimmer to west) encircling it. Companion intermittently possible on eye trick aversion. So - even on the best nights - only an ambiguous sight of Delta-B. (I can stand a litle pain...) The Double Double through Argo - impeccable. Eta Draconis: Almost easy with faint 4th harmonic diffraction ring. Delta Cygni: Just as easy but also with 4th harmonic. Stars near Ring: 13.1 direct. 13.4 slight avert at 180x. Ring itself: Occasional views of scintillation within the flanks of the annularity on opposing sides! (Don't know what magnitude these are - but the visual effect is like seeing sparkle of gen on beautiful heirloom...)

The Great Hercules Cluster: And i thought M55 was incredible! M13 was fabulous last night. Hundreds of stars - even across the core. Intriguing star chains thrown outward - especially north and south. And to "top" it off: A single diamond-pointed, radiant blue 13th magnitude star just east of core showing absolutely no hint of shyness about being seen direct.

Time was about 11:45. I'd had enough. Pleasure, like pain, should be managed - otherwise you pay the price of excess. Scopes away. There will be other such nights - and other such sights...

Odds 'n Ends

The observing session started early and ended after previewing a couple of studies planned for later in the season. Mars is well up and can be easily caught in the finderscope by 8:15 (or so). As of late this is a rather unsteady time to be observing. Noticed a calm before and after with a breeze between. The breeze seems to come up just after sundown, shakes things up a bit for a half an hour or so then subsides.

Since Argo typically suffers tube currents about this time, the Pup gets the bulk of my attention. The thrust of most of this attention has been prepping the Pup for the "Delta Cygni Challenge".

Late in the afternoon I took he Pup's lens cell apart and made some "adjustments". The adjustments come out of the fact that Delta Cygni pair has evolved into a sort of "crucible" for optical refinement. Most scopes - 60mm or so in aperture and greater - could probably resolve it, but only if in "top form". Here's the AstroTalk at astro.geekjoy.com report posted last evening on this topic:

"Early this evening pulled the object glass out of the Pup to see if there was anything that could be done to improve the collimation. Decided to bore out the mounting screw holes in the lens carriage a wee bit. The idea was to give it a bit of slack so the lens angle could be skewed a little during cinch down...

Loosened the collar and re-retested: GOOD AS OLD! Adjusted the lens position a wee bit. Turned the Pup on Delta Cygni. There it was - the little companion - quite bright actually. Averted vsion NOT required. A definitive sighting. Had previously been losing the star in Delta's slightly outsized and skewed 1st diffraction ring. Now the 6.4 mag star stood on its own..."

From this went on to view Barnard's Galaxy through the Pup. Idea was to see if this large low surface brightness study could be detected by a smaller instrument using low magnification. Posted a report on that one as well:

"Tonight (Friday, August 17, 2001) with maybe a 5.0ULTM sky was able to track down Barnard's Galaxy using the 80mm Pup at 27X. The main reason this was possible was that i am now quite familiar with the galaxy's location and what to look for.

At 27x the Pup condenses the image more than 150mm Argo can at 52X. However, the sky is much brighter at 27 than 52 so contrast is lost by the Pup.

On a really dark night the 80mm would probably give a slightly better view because of the lower magnification. But unfortunately I don't seem to get "really dark nights" in Backyard, Boulder Creek.

Whatever happened to those Summer electricity blackouts forecasted for California earlier in the year?"

Just now added last nights view through the Pup of Planetary NGC6790 to AstroTalk as follows:

"Now that I know where to find this study and have become intimately familiar with the asterism it is embedded in, decided to track it down with the 80mm Pup. Had no difficult seeing the planetary as a very small star, but unlike the view through 150mm Argo, there really isn't a whole lot to see - especially at the 70x used at the time. I imagine I could have run the power up and added an OIII filter but frankly there is little to recommend taking any heroic measures along these lines at this aperture..."

Since I was in the neighborhood dropped by 6.0/6.8 magnitude 1.4 arc-second Pi Aquilae. Stacking up all I had at the time (180x), was unable to do more than possibly make out a vaguely elongated "teardrop" double. And even this very ambiguously.

Earlier, had viewed Delta Cygni through Argo. Got a definitive but messy split... Seeing conditions were 7/10 at the time as confirmed by a preliminary check of the Double Double. As the night progressed, noticed that stability deteriorated to 6/10.

Also turned Argo on the Ring for some limiting magnitude checks. Found that, under 5.5- conditions and at 180x, could almost hold the 13.4 magnitude test star if I wrapped a towel around my head and contemplated it for awhile. - One peculiarity, all the effort tired my right eye and just as I was starting to hold the star - lost sensitivity...

Before putting Argo away, turned up the keystone asterism associated with the Crescent Nebula. The usual glow around the brighter stars was there - but so was a faint wisp engulfing the entire asterism and beyond. First definitive sighting had in several weeks.

From this point on turned 27x Pup on the Veil Complex and North American Nebula regions. Of the Veils, only the Western gave a detailed view - Eastern and Northern both require an OIII filter through the 80mm.

Had no trouble seeing extensive brightening west of Zeta Cygni. Despite this, was unable to get a sense of anything "American" - north or otherwise - about NGC7000. However, was just barely able to locate the tenth magnitude 7 arc-minute cluster NGC6997. Nothing of resolution at 27X - just a vague will'o wisp...

It was however a nice way to wrap things up and I'm really looking forward to diving into this region over the next few observing sessions...

SCAC Star Party Potpouri

The night was young and I arrived at SCAC's Bonny Dune observing site well before skydark. Even so, wasn't the first member on location - David with daughter Mari (along with young friend Ben) - had already setup their 100mm Orion-Vixen achromat. As Argo was assemble, David and I chatted amiably. He had been observing a couple years now. And daughter Mari showed a great deal of enthusiasm for the night sky. (In fact all I need do was leave Argo unattended for a few minutes and there she was turning the scope on planet Mars or its Rival.)

Dean arrived with his 8 inch SCT not too long after. He had driven the hour or so south-southeast from Half-Moon Bay. Since Dean frequently observes out of Fremont Peak we talked about experiences there. We tended to agree that the Peak wasn't quite what it used to be. Between Salinas light dome, and construction of a new California state prison, sky transparency had degraded. As this particular night progressed, it became pretty clear to us both that - at a comparable altitude (some 2500 hundred feet) - and despite light dome issues of its own (to east and north), the Bonny Doon observing site was quite possibly superior to the Peak. This, because the sky above, to the south and west sky were so exceptionally transparent, but primarily because atmospheric stability proved to be consistently good to excellent.

Speaking of sky conditions, posted the following AstroTalk report earlier today:

At last nights SCAC star party (Saturday, August, 18, 2001) under 5.5 - 6.0 ZULTM skies, had a chance to check the Ring region through 150mm Argo, a Meade LX-50 8 inch SCT, and a 14 inch truss tube Dobsonian.

BTW: The 14 inch was not up to showing the 15th magnitude progenitor star of the Ring.

Despite arriving early, Argo failed to stabilize enough to get good views of Antares and Mars before skydark. Sense is that the 150mm MCT ends up trailing behind changes in temperature as the evening air cools. Of course, it doesn't exactly help that the scope arrived warm either...

Despite tube currents and early evening instablity, Mars could be seen to show hints of temperate maria. Presumably widespread atmospheric turmoil remains in abeyance. Did manage to look at Mars through Dave's 100mm achromat. The view was comparable to what was seen through Argo at the time. Considerable chromatic abberation was visible - so it is unlikely that this particular scope uses a flourite element in the object glass. (Non apochromatic.)

By skydark, neighbor Dean and I were off and running comparing globular clusters through the 150 and 200mm scopes. In every case, the extra 50mm of diameter gave visibly brighter images. Resolution of globular components was also slighly better - due specifically to the extra magnitudinal reach of the scope. I've now compared Argo's views two 8 inch Meade SCTs at SCAC star parties. Dean's LX50 and Dwight's LX200 have both acquitted themselves honorably. Argo's views of globular clusters are perhaps a tad closer to SCAC club member Dan's FS102 Takahashi Apochromat than to Dean and Dwights pair of 8 inch SCTs. This amounts to another good reason to have Argo's surfaces coated with high-efficiency surfaces and upgrade the mirror diagonal. Such changes would clearly shift Argo more toward 8 inch performance in terms of light gathering.

Dean and I started out west with the fabulous M5 globular in Serpens. Both scopes showed at least one hundred stars across the core at 120x. From there, moved on to the "Twin Clusters" M10 and M12 in Ophiuchus. It was here that I noticed something unexpected: The clusters really aren't "twins". M10 appeared considerably rounder and more condensed than M12. A significant amount of resolution was seen in both clusters - certainly several dozen stars. But M10 gave an appearence more like M5 seen before it. No question. I'll need to spend some quality time with these two clusters to really make a definitive comparison.

While Dean mounted a camera on his scope (for a star field capture), I spent a good deal of time on globular M14. On such a good night, hoped to get a better sense of resolution. Backyard Boulder Creek's views to the south tend to be a bit marginal. As previously mentioned, seeing is exceptionally good to the south at the Bonny Dune site. Here follow a few field notes on M14 from last evening: "Large elongated core region oriented east-west, brighter to west than east. Two or three dozen stars hang right on the threshold of visibility at 120 and 180X..

Contemplated globular M9 as well: "Elongated core region. Center offset west. Dozen stars visible under moderate aversion at 180X. Best view of the cluster at 120X."

From M9, dropped south to Scorpius and M4. Numerous stars resolved. The six or seven that make up the"String of Pearls" across the core were quite evident. Next: M80 - very small and condensed. Only a handful of outliers possible at 180x. This has been and remains one tough customer! Needs more aperture and higher magnification to reveal anything of its mysterious goings ons.

Swung over to have a look at Open Cluster M7 - above the Scorpion's tail. Then on to 9.9 magnitude 4 arc-minute globular NGC6453 found near its frontier. No problem finding it due west of the core. Showed it to Dwight and Dean - both agreed that it was very near the limit. Strangely, the view through the 200mm SCT was not much improved over that seen through 150mm Argo.

Had two views of incomparable M13 during the evening. Dean turned it up in the 200mm. - Slightly brighter view of that normally seen through Argo. Jack turned it up in the 14 inch Dob! Simply incredible - must have been a thousand stars visible. HUGE! Star chain effects down played due to the many faint members filling the voids outside the core. As fine an instrument as Argo is for use with globulars - aperture continues to make the difference between presence and PRESENCE. You just don't have to work very hard at anything when using one of these big scopes - nebulae, clusters, galaxies - eveything except double stars and planets. (This is where smaller scopes tend to excel.)

Before leaving M13, Dean and I turned up the small edge on galaxy northeast of the globular. Here's where that extra 50mm really helped out. No trouble picking out 11.6 magnitude 3x1 arc-minute NGC6207. Based on this - and other experiences - its pretty clear to me that 200mm is very close to the minimum aperture for galacticians. However, I have yet to see what would be possible with that hypothetical, high contrast 140mm F7 apochromat or the 175mm F12 Maksutov Cassegrain (with enhanced coatings!).

At this point broke off from "free observing" to tackle a few studies from the observing plan. First on tap was 8.3 magnitude / 7 arc-minute globular cluster M71 in Sagitta. Despite its ease of location (Sagitta may be small, but is quite identifiable), the globular is a challenge to pick out in a 7x35mm finder. In fact, tried several "suspects" before actually catching it in the one degree 52X eyepiece.

The M71 globular lay well overhead at the time. Sky looked extremely dark in the eyepiece. The globular's field may not be as rich in stars as the Milky Way - but is nevertheless well populated. The cluster lies 20 arc-minutes due east of a sixth magnitude star. A ninth magnitude star lies just south of its visible frontier. Perhaps 3 x 4 arc-minutes of the cluster possible. At 50x, starlike core - but higher magnifications (120x) showed this to actually be a star (of about the 13th magnitude). The interesting thing about the cluster was the unexpected number of stars lying directly on its line of sight. In fact, one string of 13th magnitude stars cut east-west right across the cluster's core. (These were only visible at 180x.) Assuming the bulk of the stars seen in and around the cluster are members, then M71 is probably the dimmest cluster yet viewed that shows obvious resolution.

Had viewed the Dumbbell Planetary before dropping in on globular M71. Decided to return to do a writeup. Treated the nebula before but felt it made sense to contemplate this fabulous study like the others documented over the last ten or so months.

Planetary M27 is unquestionably the brightest study of its kind encountered in my astral journeyings. It is also unusually large for a planetary. Both these facts suggest that it lies quite close to our own system. Unlike globular M71, planetary M27 is an easy locate in the 7x35mm finder. Vulpecula "the Fox" is an extremely obscure "constellation". In fact it is so obscure that I personally make no reference to any of its members in locating the planetary. The usual method is to just begin sweeping the sky using the finderscope after first "pointing" Argo in the general direction of the southern corner of a rectangle that includes Gamma, Epsilon and Beta Cygni (Albireo).

The planetary takes up about 8 by 6 arc-minutes of apparent space. And is oriented south-southwest to north-northeast on its "apparent" major axis. It's description of being "Dumbbell" in shape is a bit of a misnomer. It appears more along the lines of a partially eaten apple. The apples "waist" is not nearly as severe as one might expect. The brightest quadrant of the planetary lies southwest. In general, the southern frontier is quite well defined - while that to the north remains diffuse. The waist of the planetary is also diffuse - especially at 50x. At 70x, several stars embedded in the nebulosity emerge - especially southwest. As magnification increases, the applecore's waist begins to "pinch" more obviously. Additional stars emerge - some in the northern region. None could be held direct - even at 180x. Basically they are seen as a scintillation on the surface of the planetary. The effect is very satisfying to the eye and gives a sense of "livingness" to the planetary. On occasion, even the dim 13.5 magnitude star hidden in the planetary's midst reveals itself through this phenomenon. The planetary is very nicely framed by four 9th and 10th magnitude stars. These take up the cardinal directions in a 15 arc-minute sized "kite" with planetary at center.

Had a chance to view the Dumbbell through the 14 inch truss-Dob. SCAC club member Jack is also a member of the SJAA (San Jose Astronomy Association). Jack borrowed the scope from the association and was most generous about sharing views with SCAC members that turned up. While I pursued my observing plan, Jack spent a lot of time with Dwight, Dave, Mari, and Ben touring the Milky Way through the big scope. By 1:30am, everyone had left but Jack and I. With Argo stowed joined Jack on a tour of a few choice studies. Among them the Veil Complex, North American Nebula, galaxies M31, 32, & 110 plus the Saturn, Ring, and Dumbbell planetaries. The following report was posted on AstroTalk based on certain of these observations - with an eye in particular to the view of NGC6888 - the Crescent Nebula.

Last night at the Saturday, August 18, 2001 edition of a Santa Cruz Astronomy Club (SCAC) star party, had a chance to view the Crescent Nebula through a 14 inch Dob. Preceding this were extensive tours of the entire Veil Complex and portions of the North American Nebula.

One more thing... This entire region of Cygnus is filled with hazy nebulosity. Many stars are embroiled in it. - It isn't all just "star haze".

Not mentioned in that report is what was seen of the Dumbbell... Through the 14 inch, (with nebula filter) - it really isn't a Dumbbell at all - nor is it a half-eaten apple - it's an "egg". That's right, an egg. Through 150mm Argo, the waist simply looks diffuse - nothing particularly well defined about it. Other than the southwestern quadrant all edges simply "bleed off into space". This same appearance can be seen through the 200mm. The southwestern edge gives an "arc-like" appearance - while the rest of the planetary remains diffuse. Through the 14 inch, this diffusion extended well out and away from the planetary waist. In fact, the east-west axis expands so much that is takes up more apparent space than the part most observers consider to be the "major axis" of the planetary. So, the cluster goes from being something like 8 x 6 arc-minutes oriented roughly north-south to 12X8 oriented east-west.

Personally - never guessed that this was the case. Going to have to pay more attention to photos of the planetary in the future...

Had one final personal study for the evening - M57 - The Ring Nebula. Like the Dumbbell, decided the Ring needed a "formalized treatment". Had absolutely no trouble turning up the King of Rings. It is an inexhaustible fount of insights, challenges, teachings, and observations. The Ring continues to engage me despite dozens and dozens of visits over the last year or so. Along with M31, M42, and M13, the Ring is the only other deepsky study I remember viewing as an eleven year old with the 4 inch Dynascope available to me at the time...

The Ring Nebula lies in a rich non-Milky Way field between Beta and Gamma Lyrae. Gamma is easily picked out in finderscope as the brighter of a pair of stars which align with the planetary. The Ring is not visible in the 7X35mm finder. I just set the crosshairs halfway between Gamma's finderscope companion and Beta. Then sweep around until I make out the annularity (typically, but not necessarily, at 52x). The Ring lies in an unusal region. Southwest is a "cocktail glass" asterism whose cup faces more or less directly toward the western asae of the ring. I've given this group a personal appellation: "The Chalice of the Ring". It is comprised of about six tenth and eleventh magnitude stars. East of the ring are no bright stars. A 13th magnitude star lies very close to the eastern ansae. On a better night 150mm Argo allows me to just hold this star at 180x. On the best nights, it can be held direct at 120X and an even dimmer 13.4 magnitude star well away from the ring can be seen to the north-northeast. (Last evening's star party was held under such a night.) Between these two thirteenth magnitude stars is one of magnitude 14.1. The three make excellent test studies for atmospheric tranmsparency as has been discussed earlier in this report.

The Ring itself is clearly annular and appears to be about 2x1 arc-minute in apparent size. The major axis orients roughly east-west. Its central "void" is about half this in size. It is a rare (and poor) night when the Ring's annularity can not be made out. On such occasions the void "smears" into a poorly defined ellipticity requiring averted vision to make out the darker center. Needless to say contrast must be pretty bad for this to happen.

When contrast is very good, and the sky is especially transparent, an effect similar to that seen with the Dumbbell planetary occurs. Two stars can be seen scintillating with the flanks of the Ring to north and south. Happily, this was, in fact, the case last night. This effect became apparent using the 15mm 120X eyepiece - a magnification which could easily hold the 13th magnitude star just east of the Ring's major axis.

The Ring itself is not a true "ring". It is actually quite elongated and gives the sense of "a single eye opened wide in surprise". It's color, like many planetaries, is "robbins-egg blue-green". Last night, I took especial care to notice which flank of the Ring is brighter. To my eye, the northwest flank appeared slightly brighter than the southeast. Also took note of the ansae: Eastern ansae is brighter than the west - which almost appears truncated in appearance. So there's a vague sense of an insect cacoon about the Ring - but not very obvious...

At very high magnifications, the core is visibly "brighter" than dark space around it. Apparently this is one reason why the fifteenth magnitude central star is such a tough catch...

Had a look at the Ring through the 8 and 14 inch scopes. As mentioned above, both scopes shared a similar 14.1 magnitude direct threshold limiting magnitude. To be accurate, the 14 inch had a 70X eyepiece loaded, while the 8 inch had 120X on tap. But the view of the planetary itself was cleaner and crisper in both Argo and the SCT than the Dob.

This points up how difficult it is to fabricate high quality parabolic primaries in such large apertures. This reality was brought home by Dwight who mentioned that he's been working a mirror of similar aperture for about three years now. Dwight also went on to say that he is closer to completing a ten inch project - started much later.

The big light buckets do have there uses though: Galaxies! We turned the 14 inch on M31, 32, and 110. The most telling view was that of M110. In Argo this 8.0 magnitude, 17x10 arc-minute dwarf elliptical is a hazy patch of nebulosity. Through the 14 inch it looked like a miniature of incomparable M31 itself!

If you love galaxies, you need all the inches you can get - even if not particularly well-shaped nor finely figured.

Pacific Ocean Marine Layer Subsides

The last few evenings (Sunday and Monday) blest me with a good excuse to get some much needed rest after almost a continuous week of nightsky activity. A marine layer - normally held at bay by higher summer temperatures - rolled in off the Pacific Ocean. Resulting clouds obscured most of the stars and I chose not to pursue the remaining "sucker holes". As mentioned elsewhere in these reports, I've come to really appreciate the occasional break from observing since such interludes work wonders in restoring my enthusiasm for the night sky.

Well before nightfall, had a chance to "tune up" the Pup's optical alignment. But I'll get to that later... By early evening Mars was possible. The following report was duly logged on AstroTalk at astro.geekjoy.com:

As is my usual want, I also turned both scopes on Antares. The main concern was to verify that changes made to the Pup's collimation and mechanics would translate into a decent star image. However, the poor seeing which plagued Mars also disturbed Antares. (Early evening skies of late have been very unsatisfactory stability-wise.)

Took a break for dinner. On return, sky had darkened up nicely. The following Astrotalk report covers a series of observations done with the Pup beginning around 9:30...

While observing with the Pup, decided to do a limited magnitude check with the aperture stopped down to 43mm. From AstroTalk:

Now I haven't posted everything on AstroTalk. One item of interest was inspired by an email from a fellow observer from Ireland (Neil). Neil mentioned having problems getting a well resolved view of Globular Cluster M13 through his ten inch Dob. Certainly Neil's observing locale is a factor (unaided limiting magnitude roughly 3.5) and possibly Neil's scope needs some collimation. Turned Neil on to AstroTalk for more dialogue on the subject, but meanwhile gave M13 a view through both scopes to describe what is possible under the usual conditions I observe under with both scopes.

Basically, under 5.4 ULM skies (local to M13), 150mm Argo (at 120X - 15mm Ultrascopic eyepiece) resolved hundreds of stars using moderately averted vision - many right across the clusters core. Meanwhile, when looking at it direct, probably one hundred stars could be held direct - several on top of the core. In addition, much star-chaining was possible - especially arcing outward to the north and south from the core region. (This gives it a "scarab" appearance to my eye.)

Through the 80mm Pup and also at 120x (10mm Ultrascopic with 3x barlow), maybe 75 stars could be seen scintillating on eye movement. Some 2 or 3 dozen could be held with moderate aversion, and a handful were possible direct. There was no evidence of star-chaining whatsoever. While using the Pup, suspected that Neil is seeing something similar through his 10 inch under 3.5 ULM conditions (at a comparable magnification). (It's doubtful Neil would have been dissappointed with a view like Argos - especially under 3.5 skies....)

Another study not posted on AstroTalk, had to do with the view of the Ring Nebula through the 43mm / f9.3 aperture stopped Pup. I was interested in determining if the "central hole" in the planetary was visible at this aperture. The result: Sure - but you have to avert - just slightly. So the sense is that any 50mm refractor should reveal that the King of Rings is, in fact, a "ring" through 5.5 ULM skies.

Also took a look at 2.8/8.2 4.8 arc-second Eta Draconis through the Pup - but without the aperture stop. Absolutely no go under the circumstances. I look forward to attempting it on an 8/10 stability night - though Eta is sinking fast...

There was one other study for the evening. This came out of an interesting Challenge Study posted on AstroTalk related to Barnard's Galaxy:

theAstronomer piqued my interest while dropping the phrase "the appearance of very rich open cluster". So I just had to run up the magnification a bit and see if any of this "stardust" would shine through.

In reflecting on last night, realized that I had yet to do that definitive comparo between M10 and M12 in Ophiuchus. With the Moon having entered the First Quarter - I'd better have at it. I wonder, should I get Argo out tonight? Hmmm...

But for a Stable Southern Sky

Again this evening early wind and general sky instability was the order of the southern sky. Overhead, but later things became quite stable and dark - but this did nothing fore Mars early on...

That first 180x look at the Red Planet proved that - despite inability to achieve focus and perceptible atmospheric boiling - the Martian atmospheric situation has completely changed. No more maria obscura. Syrtis Major just hung there - squarely approaching the planets central meridian. The NPC displayed some - but not extensive - limb haze. Switching over to a 240x Kellner/1.33x barlow combination improved image scale noticeably. Adding filters highlighted several brightenings visible on the planet's surface - in particular a strangely divided Zen Lacus just beneath the SPC.

While sketching, was once again reminded how important it is to look for the various brightenings visible on the planets surface. Such brightenings, in combination with the continent like maria, polar caps, and limb haze, make the planet a much more variagated study than when brightenings (laci) are ignored...

Mars sketch was complete before dinner. Skydark still lay a ways off. Finished a rather hasty meal then returned outside to setup the Pup in the south viewing station. After a few moments had Globular Cluster M10 in the 100x field of view. (I'd intended 120x - 10mm with 3x barlow - but ended up with the 15mm in the focuser. No idea how it got there.) Overhead the four stars in the Lyra parallelogram just visible. (The dimmest of which is magnitude 4.5.) Ophiuchus still lay east of the foliage that obliterates the southwest sky.

Had earlier taken a look at the crescent (20%) Moon through the Pup in the 43mm F9.3 mode. At 100x the view was a bit dark but still sharp - except for visible edge boil caused by low sky position and general low sky turbulence. I'll try the F9.3 approach again as the Moon brightens. Despite rsolution loss, the view may prove to be exceptional since the Pup basically becomes an apochromat at the longer focal ratio...

Had a wee bit of difficulty tracking down M10. The Pup's 1 inch finder seems to be a bit aperture starved and the sky still had yet to achieve true skydark. As I completed my notes on the cluster noticed that 4.7 magnitude SAO 160118 east of Zeta Ophiuchi could be held cleanly direct. Certainly the local unaided limiting magnitude approached 5.0 at the time...

First Up M10: The following are my scrubbed eyepiece notes: "2-3 arc-minute core region with vague, slightly offset brightening to north. Flattened to west and distended east. Dim halo practically triples the size of the cluster to maybe 4X6 arc-minutes oriented north-south. Core region elongated same direction. Surface appears rough. Scintillation possible on extreme aversion. Two or three dozen stars on the brink of resolution."

Next up M12: "Lacks M10's obvious core region. CLuster better attended (by a small group of closish field stars). Tenth magnitude blue star hangs right on the globulars southwest frontier. Vague hints of core region brightening. Luminosity spreads out gradually. Less visible flaring opposite flattening than M10. Obviously rougher - seems more loosely constructed. Like M10, a few dozen stars hanging very close to resolution. These can almost be held at extreme aversion. Some near-resolves over the core."

The sense I got through these views were a pair of largish, faint globulars, hanging right on the line of potential resolution. Just outside the range of the scope and the night. Through Argo I would have thought them of the 8th magnitude - right on the verge of resolution.

But something was wrong. Seemed to remember getting some resolution out of both these clusters through the Pup in the past...

Oh brainless one, you forgot to remove the aperture mask! Just documented how this pair look through a high power, apochromatic, 43mm photographic guidescope!

Ok, go back and make a quick check of both clusters at 80mm...

M10 Through Pup: "Scintillates direct using soft eye technique across core. (No need to avert whatsoever to see a dozen or so stars on the limit.) Under moderate aversion, dozen or so stars held direct. The globular is definitely blue (as opposed to grey at 43mm.) Where no outlier / field stars were seen near the frontier at 43mm, perhaps four or five could now be seen. Overall this cluster showed best with some aversion of the eyes...

M12 Through Pup: Perhaps a dozen stars scintillate on soft eyes. Two dozen held on aversion. Several outliers hinted at using the 43mm are now obvious. Less blue than its confrere. But due to looser constitution the cluster is more satisfying to the eye in an 80mm scope at 120X using direct "soft eye" contemplation. M12 is effectively closer to resolution.

By this point sky depth is now slightly better - certainly 5.0 - but Ophiuchus will soon duck out behind the tress. So quickly, 150mm Argo's turn at 120x...

M10 Through Argo: Large shaft of stars skewer the core along north-south axis. (Otherwise, the cluster appears quite round for a globular.) Blue color quite obvious. Two dozen stars held direct without real effort. Several even seen before the core. Truncation to west very obvious. No sense of star chaining, but still a fine, partially resolved view through a six inch scope.

M12 Through Argo: Very elongated and indistinct core region - oriented north-south. Obvious linear shaft of bright stars also running north-south at core west. Not quite as blue as - and certainly not as condensed as - M10. However, more stars seem held direct using "softeye" technique. Has a more populous field - including a "cochlea spiral" of eight or nine eleven to thirteenth magnitude field stars. (These originate from the north, arc east, and unwind to the south.) Quite possibly a precursor to "star-chaining".

Both clusters gave fine views through Argo - no special techniques needed to see dozens of members. Blue color obvious. M12 less distinct core and is more open. M10 rounder, more obvious core, and compact. Both clusters have integrated magnitudes of 6.6. Both extend 12 arc-minutes in apparent diameter. Each bears an average surface brightness of 11.7 - yet one (M12) echos the brighter, more open and elongated M4 in Scorpio. While the other reflects the more classically globular, brighter, condensed M5 in Serpens.

However, there is the small matter of the "rolling pin" bisecting M10's core, and the "needle of stars" within M12. These features are more like the "String of Pearls" seen across core M4...

Later, turned Argo - again at 120x - on M92 in Hercules. (Great Cluster's sibling.) At magnitude 6.5 and diameter 11 arc-minutes, M92 has an average surface brightness .3 magnitudes more luminous than the two Ophiuchan clusters. Add to this M92's superior sky position (ZULM=5.5) and one would expect it to give the superior view. In fact, even at 120X, M92 showed subtle - but perceptible - "star chaining". This particular feature is only seen in the very finest half-dozen or so globular clusters visible in the sky (while using a 150mm scope from 37 degrees north latitude).

Turned both the Pup and Argo on the Double Double - attractive but not perfect splits. Delta Cygni in Argo gave the classic 7/10 seeing stability result: Dim airy-diskless star just outside the spurious image of the primary - a primary which lacked itself diffraction ring and airy disk.

The Pup however was having a slightly more stable night. Single, very dim first diffraction ring surrounding Delta's gorgeous round disk. Obvious and persistent brightening to southwest. Brightening appeared somewhat distended - not a point. But obviously something other than a weird zone in the lens. Unambiguous, persistent resolution using the 10mm Kellner backed by 2 element shorty-shorty barlow for 160x. The best view of Delta Cygni's companion yet through the Pup - and the result of time well spent collimating the mechanics.

Using this same combination did the M57 deep starfield check. For the first time found I could hold the 13.08 magnitude star east of the Ring with extreme aversion through the Pup. Had no trouble holding the 11.6 magnitude star in the Chalice of the Ring direct - even as a point. So appears that under 5.5 skies the Pup can reveal 12.0 magnitude stars direct. A new milestone!

Meanwhile at 180X, Argo showed the 13.4 magnitude star direct. This lasted only briefly - then my observing eye gave way and I was back to barely holding the 12.8 star.

One new study for the evening. Fellow observer Cor Berrevoets posted AstroTalk data on 6th magnitude double star STT410 in Cygnus. Under tonight's 7/10 stability seeing - and using only 180x - had no trouble resolving this .9 arc-second pair as "tubular" (with the possibly dimmer member north-northeast). Popping in the 240X Kellner-shorty combo was enough to occasionally discern the finest of hairline splits. This as the sky suddenly stilled and two, small, pearly white, airy disks would float lazily past just kissing at their extremes. No question that not much more magnification would have made clean resolution definitive. Interestingly, the same kind of leading edge "wave of brightening" seen on other matched pairs appeared.

STT410 is well attended. The pair and three 7th and 8th magnitude stars formed a long east-west oriented diamondof stars. It's always nice to spend some time contemplating the setting along with the jewels...

Sky and Mars Refuse to Dance!

Sorry folks, skydark is still a ways off but Mars and Selene are calling to me - have to make this one a "quickee"... Started last evening off with a view of Selene hanging above the northeastern roof (of the house). Spent a good deal of time dwelling on Posidonius (as per the following report posted on AstroTalk):

Had a chance to view the crater as it lay just off the terminator tonight. Contrast was excellent, but sky stability was at best 6/10. Could tell that the mound west of the Posidonius central crater was double - but not a clean resolve. Group of three small mounds could be readily detected southeast. Some hints of a crater or depression possible near the main craters trailing (eastern) wall. Best view at 140x using 150mm Argo in the "straight through" viewing mode (no diagonal).

The went on to view Mars. Conditions were better than the previous night - at least here on Earth. On Mars the story was different:

Due to high thin and variable clouds, plus moonglow - sky never really got dark down low - maybe 4.5ULM in Sagittarius. But had a look at "The Truly Great Cluster" - M22. One thing noticed was an arrowhead of stars pointing toward the core near the northeastern frontier of the core region. This particular group of 12.5+ magnitude stars only become obvious at 140X. Even at 240x, the group required slight aversion to hold. One reason the group was seen may be due to the fact that the region around it seemed relatively devoid of bright stars. This became apparent to me at the highest magnification used (240x)...

Also took a peek at M28. Maybe half a dozen stars "flashed into view" at 240x. Once again I would say that, under better conditions, this particular cluster - and ones like it - give the "optimal" view when using an optically correct 6 inch scope...

Speaking of "optimal views by aperture", found that the 43mm F9.3 configured 80mm Pup came reasonably close to reproducing the view Argo had on M28 while studying M13 at 100x. Able to get a sense of cluster orientation (east-west), flattening (to south), flare (to north), core size (4x3 arc-minutes) and central brightening. There was no star-like point, but possibly a dozen stars hung on the limits of resolution seen as "softeye" scintillation. Hope to get a view on a 5.5 night to nail it - but yes - it does appear that a 50mm scope gives a decent view of the Great Hercules Cluster, just as the same aperture just reveals the annularity of the "King of Rings" - M57 on a 5.5 night...

Finished the evening with a quick check of Delta Cygni through Argo - (typical 7/10 seeing stability split) and limiting magnitude checks (as follows):

A Less Than Inspiring Night Out

Ok, you've heard all this before. Sometimes observing is a discipline, sometime's an art, sometimes its inspirational, and sometimes not. Disciplined viewing is always a pleasure to me. There's something about having a plan and moving it forward that is intrinsically satisfying to my nature. The problem with disciplined observing is that it is just not possible under marginal observing conditions - like last night.

Artful observing can be as joyful as disciplined observing - but lacks an agenda. You just open yourself up to the sky and let it tell you what it wants to tell you. But artful observing is most likely to happen when you're well rested and haven't observed for quite a while. To observe artfully you need to be receptive. Artful observing is less dependent on sky conditions - why when you haven't observed for a while - you'll even chase "sucker holes" around the sky!

Had a late start getting at it last night. Had to finish the previous evenings write up. As I did so the Moon drifted behind the southwest foliage. What I did see is captured in this report filed on AstroTalk):

Also took a look at Mars - but the sky down low was especially poor this evening - probably 3/10 stability. Hopeless!

Did have an agenda for the evening. But due to sky conditions was not getting the definitive view needed. The goal was to determine if M13 would give a "satisfyiung view" through the 80mm Pup stopped down to 43mm. Here's the write up on AstroTalk:

Speaking of conditions, toured the usual doubles and the M57 deepfield. Here's the report to AstroTalk concerning limiting magnitudes as seen under 6/10 stability 5.0ULTM:

Did go after one test double posted by Cor Boerrevoets on the AstroTalk Double Star board. Here was my response to the posting before actually tracking down the study (BU 265: Magnitudes 7.4 & 9.3, Separation 1.4", Position Angle 227°):

The following is the write up on this pair from last night's observing session:

I wonder if Argo will resolve it tonight?

Refreshed and Rejuvenated

Yesterday hit a bit of a trough in my enthusiasm for observing. Like most things in life, amateur astronomy has its ups and its downs. All has to do with energy - sometimes the energy's flat and sometimes its where your at. The "intelligent observer of life" recognizes this phenomenon and accepts both highs and lows with equal aplomb. Ain't saying I'm a particularly intelligent observer of energy-flux, but at least I'm aware of it and its impact on psyche.

Speaking of Psyche, found myself really enjoying the Moon this evening. Decent sky stability (6/10) and the emergence of some favored features (the Alpine Valley for one) conduced to some real Selene quality time. Dawdled over Posidonius - occasional snatches of the "twin mounds" at 360x. At times may have distinguished between the mounds (west of the central crater) and the fact that the "mound" north of same is actually a small crater. Easily located Crater Messier - though it lies well past its terminator prime. Noticed the twin rays emanating out of Pickering to Messier's east. And the "winglike" brightening running north-south that engulfs Messier itself. (Total effect that of a "Bird of Paradise" winging its way across Mare Foecunditatis.) Detected three small craters just west of the Alpine Valley. One of the three (the northeasterly) looked more like a volcanic caldera than a crater. The valley itself looking like a stilletto thrusting toward the more southerly pair of the trio.

Doted over the emergence of Aristillus and Autolycus north of the Alpine Valley. Noticed many fine "undulations" west of the crater pair and some extremely long cone-shaped shadows. The region was filled with a certain "frozen" dynamism. As I sketched almost got a sense that the scene was changing (very slowly) before my eyes. The area must have been very intriguing to the eye since I elected to sketch it rather than the more frequently observed Alpine Valley itself.

Despite the decent view of the Moon, that of the Red Planet was very poor - only the vaguest intimations of Syrtis Major advancing toward Mars-east.

Main study for the evening was close and disparate double BU265 in Aquila. This is one of Cor Boerrevoets' "Challenge Doubles" on AstroTalk. And it was there that the following report was posted:

Also posted on AstroTalk was the following report concerning the effects of moonlight on limiting visual magnitude:

Best Layed Plans

Had big plans for this evening. Printed off some charts for a half-dozen challenge doubles from AstroTalk. Took care of a few chores and by 8:00PDST set down to mull over the Straight Wall (Rupes Recta) region of the Moon. Started out at 180X and got a pretty decent view at that - better than most this cycle. Figured I had a superb sky shaping up. Began salivating over them doubles even as I took note of the superb contrast shown by the Straight Wall itself.

This really was my first good look at Rupes Recta. Last cycle caught it well progressed away from the terminator. Quite visible at the time - but not strikingly so - as it was this evening. Despite being close to the terminator, Rupes Recta was still well away from it. Didn't exactly take note of where the terminator fell - but certainly Nicollet (east of Birt) stood revealed.

Fellow observer Cor Berrevoets posted a sketch of the region based on a 100x eyepiece view through his 150mm Intes Micro MCT. This became the basis for the evenings observation of Rupes Recta. In response posted the following report on AstroTalk:

Took a quick look at Mars. The Red Planet would not achieve focus - even at a measly 180x. Mass of maria toward the Martian terminator was possible however...

Moved Argo over to the north viewing station. Checked Delta Cygni - if visible at all, the 6.4 magnitude companion lay just inside the flashing spurious image of the star - ouch! Double Double gave the typical "star foo yung" view of 6/10 seeing stability. Time to rethink the evenings agenda. Decided to go for a few stars in the 2 - 4 arc-second range - disparate pairs ideally.

Settled on three in Draco: Epsilon, Beta and Mu. Dropped by Eta as well.

Like Delta, 2.8/8.2 magnitude 4.8 disparate pair Eta Draconis is no friend to 6/10 seeing stability - but thought I caught occasional glimpses of the companion at 120X to the southeast...

Epsilon Draconis was pretty easy to turn up. Closest brightish star pxoximate to Beta Cephi. Epsilon consists of a 4.0 magnitude primary and a 7.6 magnitude secondary separated by some 3 arc-seconds. So a very difficult pair under the circumstances. Thought I could make out a faint blue star south of the warm yellow primary at 180x. If seen at all, was during averted vision. No idea what the position angle is on the pair. Should be a nice check to find out. (BTW: Double star calculator - dblCalc version - says the secondary becomes visible under 7/10 seeing.)

The next pair was the most difficult of the three new ones viewed this evening. Like Eta, Beta Draconis Prime is magnitude 2.8, however the secondary is a very dim magnitude 11.5 and lies some 4 arc-seconds distant. I would think this one impossible for Argo but dblCalc says it's possible on an 8/10 stability night under 5.5 transparency.

Well tonight, as already indicated stability was about 6/10. Naked eye tests overhead in Lyrae revealed stars close to 5.0 (5.0 SAO 66943 turned into a vague light pile direct.) At 120X, the 13.4 magnitude star near the Ring could just be held with extreme aversion - while mild aversion was needed to hold the 12.8 star. So the "lunar-corrected" transparency was closer to magnitude 5.3. Did I have any luck with Beta Draconis?

Hardly... Possibly a very dim star to the south and trailing the warm yellow primary. Detectable only on eye movement at 180x.

So far, two no shows (at least definitively).

OK, so let's go after Mu Draconis. Primary magnitude 5.8. Secondary magnitude 5.8. Separation 2 arc-seconds. But first what does dblCalc have to say? "Unable to cleanly separate" - under 6/10 stability seeing.

At 120X "duplicity" of the star suspected. At 180x - and with a little patience - could distinguish the pair. In fact, got the sense that the "brighter" of the two yellow white stars trailed. Very definitive split - but variable.

Kind of like the sky tonight. But not variable upward enough to go after the really tough 'uns...

Making Good Out of Bad

Sometimes things get worse before they get better. Tonight's sky was that bad. Could hardly look at the Moon. Turned my eye rapidly away from Mars. Both pairs of the Double Double elongated at 120x. (Epsilon-2 barely resolvable at 180x.) Delta Cygni's companion swollowed up by it's "titanic" primary. At 120x couldn't quite hold the 12.3 magnitude star in "The Challice of the Ring".

This last was very helpful. And made the whole evening worthwhile. It become clear to me over the last month or so that seeing stability has a significant impact on telescopic limiting magnitude. Seems the eye is less bothered by the goings on in the atmosphere than the scope - which as you might suspect is more sensitive to instabilities. But I needed some data to help me get a start on determining the degree of the effect (so it could be added to magCalc). Tonight's poor sky, (along with data from a variety of sources) gave me that start. The new algorithm basically accounts for two factors at once: Seeing stability and optical quality. The idea is that a poorly refined scope will never get the kind of star images suggestive of fine seeing. And a scope that does give good quality star images (airy star disks with stable and concentric first diffraction rings) gives you superb seeing (when the atmosphere allows it). So this important feature has been included (along with another refinement that need not be gone into in this report.)

Meanwhile, had one other piece of unfinished business, Seems I misquoted the relative positions of Mu Draconis. Despite the fact that tonight's stability was too poor to resolve this pair - I could at least tell (at 180x) the direction of elongation - namely north-south - not as reported east-west. What alerted me to this was some research on the web which says the "secondary" was to be found at position angle 9 degrees (basically north). (This same source also indicated the separation was 2.1 arc-seconds.) Note to self: Be very careful when rotating that diagonal!

It was a short night - but a productive one. What comes out of it is a good reason to observe under bad conditions - there's probably plenty of room left for tweaking the latest change to the Limiting Magnitude Calculator.

Synchronicity Strikes Again!

Every once in a while the dam bursts and moist air accumulated over the Pacific Ocean rolls in and overruns the Santa Cruz Mountains summer sky. Such has been the case the last two evenings and I, for one, was glad of it! Most observers are vexed by having insufficient opportunities to "plumb the heavens" with their instruments - and this will definitely be the case forh me during the late fall and winter - but that is not the case now... So I gets my breaks when the clouds roll in. The time off is generally welcome and easily re-allocated to other pursuits. Many of these astronomical, some more mundane.

But two nights of marine layer was enough. Backlog of double star observations growing. Soon need to return to "deepsky ways".

Last night sky remained clear until a little after midnight. By that time I had wrapped up and moved on to other things. Last night's other thing was "astrochat".

AstroChat is an astronomical chatboard setup by tech-savvy friend Dave in Olympia, Washington (who also hosts astro.geekjoy.com). Unlike AstroTalk, AstroChat supports real-time dialogs between fellow amateurs (and anybody else who may be interested). This service is always available - (but right now you're not likely to find anyone online unless you email in advance and arrange a discussion time). To use the service you need a chat client or plugin. If you are savvy in this area, just connect to the server at irc.geekjoy.com and select astrochat as channel.

Last night, fellow amateur Cor Berrevoets and I discussed, among other things, a particular double star I had trouble turning up earlier (STT 383). This particular pair is quite difficult - in fact, at magnitudes 7.1 and 8.3 separation 0.8", it is on the "hairy edge" of a 150mm instrument. The diffculty had last night was matching up chart and sky. Chart shows a second star (of similar magnitude) very near STT 383. Spent a good deal of time eyeing what I thought was the pair - but there was absolutely nothing peculiar about it's very tiny airy disk. In fact, the two neighboring stars prsented nearly identical views...

So after an hour or so of checking and cross-checking the location decided that the real STT383 was not part of any 5 arc-minute spaced line of sight double. Had to be further north in the direction of Delta Cygni...

Speaking of Delta (interrupting the plot), Argo gave a fine 7/10 stability view of the dim companion last night. Noticed the secondary appeared (as a star) just inside the primaries fourth diffraction ring. Primary itself displayed an airy disk embedded within a flashing spurious image. Sure sign of 7/10 stability. Meanwhile, the Pup at 80mm's gave a fine 8/10 view of Delta. Clean airy disk (no flashing), with almost starlike brightening right on the primaries first diffraction ring. Went so far as to stop down the Pup to 43mm. Huge airy disk. Single almost perfect diffraction ring completely circumscribing it (9/10 stabilty sign). Absolutely no indication of a secondary. (NOTE: Don't care how perfect a scopes optics, or the quality of the night sky, once the primary's airy disk expands enough to swallow up the secondary, it ain't going to be seen.)

So, in terms of the quest for STT383, sky stability a bit south of ideal. Basically, anytime you want to resolve an equal magnitude pair at Dawes limit (.8 arc-seconds in a 150mm scope), you need to have 7/10 seeing. (You need to see airy disks - but the condition of diffraction rings doesn't really matter.) However, STT383 is not just a pair at Dawes limit, it is a disparate pair at Dawes limit. This requires you get nice, well-behaved diffraction rings as well. No flashing, airy disk plus stable diffraction ring.

Now disparate pairs come in many magnitudes and separations. We've already seen that it is very difficult to resolve Delta Cygni. Delta is an example of a "mid-brightness" disparate pair. This type (primary magnitudes roughly 2.0 to 4.0) often "flash". Basically their light escapes the airy disk and often exceeds the first diffraction ring. This kind of behaviour is atmospherically induced and gets more and more severe with aperture. (For instance, the 80mm Pup usually shows Delta Cygni Prime as a nice compact airy disk while 150mm Argo - with better optics - usually doesn't.) So at best, you are only going to resolve a disparate mid-brightness pair when the secondary lies on, or outside, the first diffraction ring.

However, the brightness difference between the pair is also a factor. For instance, Delta-A is magnitude 2.8 while Delta-B is 6.4. The difference is 3.6 magnitudes. That's a factor of over 28 times! For the Pup, this difference is almost insurmountable and the secondary, at best, appears as a pointlike "brightening" on the first diffraction ring to the southwest. For Argo, the first diffraction ring lies much closer to the primary and does not play a role. Meanwhile, it's larger aperture reveals more subtle contrast, so the secondary is seen as it's own distinct star. (Under the very best conditions a star with its own airy disk and first diffraction ring even.)

Another disparate pair is Antares. It's low sky position means that seeing stability never gets as good as overhead. In fact, last evening, stability was better than usual. Mars gave a nice sharp edge and Antares 5.4 magnitude companion could be seen dancing around the flashing, spurious image of its 1.3 magnitude primary. The difference in magnitudes for this pair is 4.3 (or 53 times brightness) - worse even than Delta Cygni! However, the brighter the secondary, the better the contrast. So under 6/10 stability down-low seeing, Antares-B could be seen "dancing in the flames" of Antares-A.

Rambling on (and speaking of Mars), the seeing was so good - just had to do a drawing (despite the relatively structure-free presentation of the Red Planet at the time). Sketch was made at 360X (10mm with 2x configured barlow in straight-through viewing mode). Limb haze apparent at North Polar Cap. Little of either cap visible. No laci detected. Just that vague swatch of Mare Sirenum-Cimmerium beneath the south pole. Planet is at 13 arc-seconds apparent size now. Magnitudinally well below -1. Still a great way to start an observing session...

Early on, spent some time tweaking the Pup on Antares. Like Delta Cygni, have this suspicion the Pup can show the dimmer companion. Problem is Pup shows a definite "skew" in focal and extrafocal diffraction patterns. Rings are bright on one side of the airy disk and dim on the other. Definite collimation problem. Especially problematic since there is no pre-engineered solution (no collimation mechanism). Suspect that a "spacer" is needed between object glass and edge support. (Given up on simply re-positioning the primary's cell.) Despite the collimation issue, seemed to get a "hint" of Antare's companion to west-northwest. Won't have too many more chances to see the companion in the future. Antares is well progressed and heading into the foliage...

Did turn the Pup on several doubles last night. Confirmed the 43mm aperture stopped Pup could show the Epsilon Lyrae 2 pair as tubular (if not slightly hourglass). Also shows E-1 pair as teardropped. This at 95X per inch aperture! (That center 43mm is wickedly well shaped...) Even at 80mm the Double Double is a cinch at 120x (on a steady night). Checked Pi Aquilae too. At 160X the pair is a definite teardrop with possible houglassing - needs more magnification but right now 160x is it.

Using 150mm Argo, revisited the Draconis familiy of doubles. (Really begijnning to like this constellation!) Widely disparate Eta (2.8/8.2 4.7") showed its faint blue secondary trailing to south and just outside 4th diffraction ring. (The third is invisible and first two were intermittently flooded out.) Close hugely disparate Beta (2.8/11.5 4") a definite no show. (As was Eta's companion in the 80mm Pup.) At 5.8/5.8 2.1", Mu is easy in both Argo and the Pup (at 180x and 160x respectively). 4.0/7.6 3" Epsilon simple for Argo, but on the edge for the Pup. Double Star Calculator says this one only possible on an 8/10 stability night with a ULTM of 4.6. With Epsilon well down in the BC lightdome and a 75% Moon, it was tough - but the Moon is less a problem telescopically - especially for small apertures. (A 4.0 sky without a moon is much poorer than a 4.0 sky with one.)

With Lyrae turned the corner and heading west, did limiting magnitude checks. The 43mm Pup revealed an 11.1 magnitude star in the M57 deepfield direct at 120X. At 160X, the 80mm Pup pushed this to magnitude 11.6. Meanwhile 150mm Argo (at 180x) showed the 12.8 magnitude star direct and 13.4 moderately averted. So for the aperture stopped Pup, ULM was 5.5 under 9/10 stability. 80mm Pup was 4.3 at 8/10 and 150mm Argo 4.4 at 7/10. Once again - under adverse conditions - less is more. At the time couldn't quite make out all the stars direct in Lyra's parallelogram - so unaided ZULM may have been as low as 4.0.

Having re-visited the Draconis doubles, was ready for something new. And this is where STT383 came in. Did my usual "methodical" job of tracking it down. As mentioned earlier, unable to clearly identify the asterism shown on the chart. Due to innate stubbornness just kept trying and trying. Stayed with the initial candidate way too long. Compared it over and over again to a nearby star of similar magnitude. Despite having a nice, tight airy disk, and reasonable diffraction ring, nothing doing. Nothing about this particular star smacked of duplicity. Went further afield. Examined one star after another. Got fooled by the occasional brightening on the diffraction ring. Finally ended up about 1 degree north of the original pair. And there got a hint of a teardropped airy disk with dimmer lobe to north. Nothing definitive. But definitely not right.

The discussion on AstroChat moved on to other topics. Cor volunteered to send me another chart by email. In reviewing this chart later, discovered that somehow an "artifact" had occured. There are, in fact, two stars on both charts. But not near the real STT383. That star is solitary and north of the wide pair doted over the previous night. There is a good chance the star one degree north is, in fact, STT383.

By this time it was late. Quickly turned up a much tougher disparate pair (AGC13). Noticed the primary go through a crazy sequence of flashing, dissolving, sharpening up and flashing agin. Ugly diffraction rings on the 3.6 magnitude primary. Realized Argo was pointed straight up and down. Could body heat be rising and disturbing the air? But how could I test this theory - no way to peer through the eyepiece!

Interestingly, Cor sent an email this afternoon. He had decided to revisit STT383. From that message:

"Had a fast go over STT383, not really dark out here with thin clouds everywhere and the moon rising up. One thing struck me though, at the current position of STT383 I have more problems than two weeks ago. Being so straight overhead is not a positive thing, I am a clear heatsource when I sit behind the EP. Looking up at STT383 I can literally see the heat flowing over the scope. I sit a bit back, wait a minute, bend forward and I can see the airy-disc and the 1st ring (dim though) and a minor brightning N of the airy-disc. Cant tell if this is the secondary or a brightning in the 1st ring during this kind of thermal problem."

Synchronicity strikes again!

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