Observational Astronomy Reports -- Month of December, 2000
Reports for November, 2000 Too Much of an Otherwise Good Thing A Tale of Two Stellar Cities A New Playground of the Stars Star Party for One Let the Sky Decide for You Jupiter and Saturn Redux ... And so on Ad Infinitem. Observatum Interruptus Confidence Gained Establishing Deepsky Momentum The Fruits of Perseverence Mystery at Sea Southern Sky Deep Sky Challenge Reports for January, 2001
Too Much of an Otherwise Good Thing
Date: Saturday, December 3, 2000Earlier today I bicyled up to Redwood Elementary School to check out its potential for observational use. Recently, I had become a little disillusioned with my Boulder Creek Elementary School location due to the frequent "haze" that drifts in an hour or so after astronomical dusk. Earlier in the season I did not experience this particular behaviour but now, with the "California cold and damp" on the build, the haze scenario was becoming a bit too commonplace for my taste.
Redwood Elementary is well outside of town (about 6 kilometers). It is also higher in altitude (maybe 100 meters). I figured the haze was less likely to drift into this location (Boulder Creek is a town within a valley). The view south and west from the school is outstanding. East is somewhat problematic. The northern vista, acceptable. Having assayed this, my next concern was the presence and distribution of outdoor lights. The one free standing light near my favored spot was "boxed in" so I felt I could work around it. What I hadn't noticed was that this spot was directly in front of a wall mounted lighting unit.
As dusk approached I drove up to the school. The first thing I noticed was how many parking area lights were turned on. This surprised me. I expected that such lights would not be in use unless there was event scheduled at the school. In fact it seems to be school policy to leave them on all the time.
As I pulled up, I noticed the wall unit directly over my coveted viewing spot. And that was that.
In hopes of salvaging the situation I walked the grounds looking for a good spot on the playing field. I noticed a gate leading up to the field from another road. I pulled the car around to the gate and unpacked my equipment. With everything in place, Venus was still well above the treeline to the southwest.
Venus:
I started looking at the planet while the sky was still quite bright. I estimate that the planet was a good 25 dgrees above the horizon and about 15 degrees clear of the treeline. The view through the unstabilized scope at 360X (15mm with 3X barlow) was poor. The planet "boiled" and exhibited chromatic aberration. I tried my green filter on it. This softened it up and more sharply revealed the gibbous phase of the planet. The distribution of luminosity across the disk became quite noticeable. The sunward edge was quite bright. From this limb a very subtle transition to the middle of the globe was detected. From the centerline to the terminator the change in brightness was quite dramatic. The terminator itself was quite "fuzzy" and indistinct. Much of this was induced by the seeing conditions, and the fact that the scope was not fully stabilized. Some of the fuzziness also attributable to the "Veiled Beauty's" copious cloud layers.
By the time I finished my Venus observations, the sky had darkened enough to see that the lights in the parking lot would be no friend to deep sky. So I hunted around for a better station for the scope. Outside the school grounds proper (on the side street) was a small maintenance building. The street itself was well below the school play ground level. The bank offered protection against parking lot illumination. The building blocked the glow from a street light on the corner. There was nothing romantic about the locale, but I decided set up here for deepsky viewing.
Deep Sky:
The moon was well up in the south-southwest. It was approaching but not even close to "half moon". The sky suffered the violence of too much light in that direction. I didn't mind though because I wanted to take this opportunity to get a sense of how moonglow would impact objects I had seen in Lyra and Cygnus.
A quick check of Epsilon Lyrae showed that, by this time, the sky was reasonably steady. I got a passable (but not fully clean) split of the double-double and did a limiting magnitude check. Epsilon's 12th magnitude come was just visible (with slight aversion). I then shifted to the "Chalice of the Ring". The 12.8 magnitude come could only be seen with extremely averted vision and not with any real certainty. Ursa Minor was low, so I inspected Cassiopiae for a direct view of Kappa (magnitude 4.2). This was just possible. Doing the math, I added 7.5 to 4.2 and got 11.7 as the current directly viewable limiting magnitude. As a result I could now surmise that extreme aversion of the eye can just reveal stars 1 magnitude (2.5X) dimmer than those seen directly. Slight aversion adds roughly .5 magnitude of stellar perception. As you might guess, had the moon not been up, things would have been much better...
I checked Iota Cassiopiae. At 180X (10mm ep) I was able to cleanly resolve this triple and see the roughly 12th magnitude field star with minimal aversion. A 50X (35mm ep) view could only resolve the 7 arc-second companion. The 12.0 magnitude field star could only be barely glimpsed with extreme aversion. Keep in mind that I do not have the data on the field star's actual photographic magnitude. I would say that it is anywhere between 11.8 and 12.2. This estimate is based on comparisons with Epsilon Lyrae comes (12.0 & 12.5) and the 12.8 Chalice of the Ring field star. (These tests were done when Lyrae was high in the sky and Iota Cassiopiae was lower.)
Under the 11.7 TLM conditions, the smoke ring aspect of M57 was less obvious. (The hole in the donut was less perceptible than under better conditions.) M56 globular cluster stars were impossible of resolution and the usual "star-grain" was only perceptible with averted vision. I had no luck even fantasizing about thinline nebulosity in NGC 6888 (The Crecent Nebula).
With the moon up, I could not make out M27 in the finderscope. I had to stumble around in the main scope at 50X until it presented itself. When it did so, I was impressed with how bright it was -- under the conditions.
I also decided to take a quick look at M37 (between Cygnus the Swan and Lacerta the Lizard). At magnitude 4.6 it was just perceptible to the eye. (I am not sure if I had to avert or not to make it out.) Tracking it down in the finder was a breeze. I found that all of M37 easily fit into the 50X (1 degree) FOV. This loosely organized cluster is populated with several dozen stars ranging from about the 6th to the 10th magnitude. The shape of the cluster is slightly oblate -- along the northeast to southwest axis. Brighter stars are rather randomly distributed throughout the cluster. (There is no bright central core.) I suspect that this is an old cluster whose stars are rapidly spinning out of mutual gravitational influence...
About this time someone in a neighboring yard switched on the yard lights and that was that...
I packed up and drove to the Boulder Creek Elementary School. (I wanted to compare the seeing and determine if the haze had rolled in.). Surprisingly (and happily), conditions were indistinguishable from those at Redwood Elementary. I set up the scope. With Pegasus high overhead. I tracked down the 6.4 magnitude globular cluster M15. M15 is quite easily found. Just follow Pegasus's south-western leg to the hoof star (Epsilon Pegasi). Then extend the line formed by Theta and Epsilon out about 3 degrees. (The globular cluster appears as a fuzzy star in the finderscope even with Epsilon in the field.)
At 50X, the cluster (at 12 arc-minutes) is quite small and compact. It displays a tight, bright central core which tends to overpower the rest of the cluster. Switching to 180X I was surprised to see that I could not directly resolve any stars. With moderate aversion, several dozen stars were suspected -- but not decisive. The cluster appears somewhat distended along the northeast/southwest axis. Its eastern flank appears slightly truncated.
After observing the M15 cluster for a while, I checked the meniscus. Some slight dew was present over the surface. But the primary spherical mirror was still easily discernable. (In fact I noticed a rather poretty effect. My head was positioned such that I coiuld clearly discern a sprinkle of stars over the mirror at prime focus. Very lovely.) Somewhere between the effect of the moon, the dew, and the overbright central core I lost the ability to directly resolve stars associated with this relatively bright and moderately large globular cluster.
After viewing M15, I turned the scope on Jupiter. At 180X, the Great Spot hollow was easily discernable about 30% of the way across the disk. I could also make out the on again/off again south temperate belt -- STB. The NTB was obvious -- but not its echo in the north polar region. I wanted to go to 360X (15mm with 3x barlow) but I discovered that somewhere in my journey the thumbscrew used to latch the clock drive had fallen off and disappeared.
By this time, the moon had moved behind the treeline and I turned the scope on M31 ("The Great Nebula in Andromeda"). I had viewed M31 before but this time I hoped to really spend time on it and write up my observations.
M31 is easily visible to the unaided eye on a line extending from 2nd magnitude Beta to 4th magnitude Mu Andromedae. At 50X the elongated shape of the central core was quite apparent (spreading out along the northeast to southwest axis). The core itself is about as bright as the core of M15 but also far more extensive. "Nebulosity" surrounding the core easily extends out about one degree to each side of the core then blends evenly off into the dark of space.
The core of M31 is completely unresolvable in my scope. The northwest flank of the galaxy seems to be truncated. (Probably a dark dust lane in the galaxy itself.) I didn't notice whether there was any nebulosity beyond this dark lane. (This is something I will look for next opportunity.)
Near M31, I could see what appeared to be a highly compact globular cluster to the south of the field. This is a companion galaxy orbiting around the much larger M31. The companion galaxy (M32) has a bright compact core that fades quickly to space.
A line of field stars is apparent along the M31 galactic disk. (It makes sense to map these out sometime in hopes of catching sight of a supernova.) There appeared to be a wide sprinkle of field stars beneath M32 (on M31's disk). I assume this is the open cluster NGC 206. When I wrote my field notes I failed to even annotate this since there were so few stars.
After viewing M31, I switched over to see Jupiter again. The Red Spot hollow was no longer discernable. I had assumed during my earlier observation that it would progress across the globe to the central meridian -- but now it was nowhere to be seen.
Made a quick revisit of M1 "The Crab Nebula". Had a little difficulty tracking it down. When I did find it (1 degree northwest of Zeta Tauri) it looked like a vague thumbprint in the ep. I installed the OIII filter but it really didn't improve it much. It's hard to believe that the loss of a little more than a single magnitude (5.5 ULTM to the current 4.2) makes that much difference in contrast.
Orion was now up. I visited M42 and paid special attention to the Trapezium. Unlike the previous evening, the 7.9 magnitude component was visible. High power inspection (180X) did not show any additional components. The stars themselves were somewhat unstable (as Orion was fairly low in the sky at this time -- 9:30). M42 nebulosity was far more present than the night before (when I got "hazed" out).
Based on this evening's observations, its now pretty clear to me that, overall, the ability to really appreciate commonly accessible deepsky objects requires that sky conditions support direct perception of magnitude 12.0 stars. In my 150mm scope, this means that stars of 4.5 magnitude must be directly visible to the unaided eye. Conditions such as this evening's (4.2 ULTM) are less than satisfactory. For small scope users, the moon is an unwelcome visitor...
A Tale of Two Stellar Cities
Date: Tuesday, December 12, 2000This evening I went up to BC Elementary School to both test the new Vixen star diagonal and track down Globular Cluster M2 in Aquarius. (I've written a separate report on the star diagonal in the "Early Lights" document.)
Conditions:
Epsilon Lyrae: 45 degrees above northwest horizon. Clean split (but unstable). 12th magnitude come just barely directly visible. (Spent a lot of time viewing this until it dropped below roofline then switched to M57.)
Chalice of the Ring: Again 45 degrees above northwest horizon. Smoke Ring shape barely discernable. Chalice stars difficult. Absolutely no sign of 12.8 magnitude field star.
Iota Cassiopiae: 60 degrees above northeast horizon. Dirty split / slightly unstable. 12th magnitude field star moderately averted at 50X. Later barely direct at 180X. By this time Kappa Casseipeia was also just directly visible. (ULTM 4.2 + 7.5 = 11.7 TLTM).
Conditions just barely acceptable for deepsky. No moon, but thin clouds occasionally streaking overhead.
NGC 6888: "Crescent Nebula in Cygnus". At 50X "C-shape" stood out well -- in my imagination. At 180X nothing but the faintest swashes near southern face of the Crescent 5 in the "M asterism". But at least very little "quasi-nebular glow".
NOTE: On Friday Evening December 15 from the newly discovered China Ridge Observing Site (under 4.9/12.4 LTM magnitude / clean Iota split conditions), I came pretty close to declaring this object non-imaginary -- but still not yet.
M2: With high thin clouds beginning to build in that general direction I was able to see "Her Fuzziness" in the finderscope about 1/5 of the way between Beta Aquari and Epsilon Pegasi. First light: This globular is bright, with a broader core than M15. More nearly circular in shape but still slightly compressed toward the west. Probably 75 -100 stars resolvable at 180X using extreme averted vision. (Should see that many directly under truly "darksky" conditions.) Coarse textured at 50X and slightly larger than M15 (perhaps 1/5th the FOV -- 12 arc-minutes).
NOTE: I also revisited M2 while at China Ridge. Using the "soft eyes" technique I made out about a half-dozen stars. M2 was in the descendant zone and therefore poorly placed.
M15: Took a quick look just to compare views. What I've written earlier still applies. Still looks like it has a "supernova" at the core with surface brightness diminishing quickly outward. Extreme aversion shows that probably 50 - 75 stars will resolve on a good night.
High thin clouds now giving way to lower opaque clouds. These started to "corral" in the dark sky. Haze and fog down low. Almost time to bail, but since M31 directly overhead, I decide to make a quick check to compare its "quasi-globular" core with the globulars. Yup, what I suspected, no amount of averted vision is going to show any coarseness or resolution. What I'd seen in M2 and M15 is for real...
A New Playground of the Stars
Date: Friday, December 15, 2000Over the last week or so I've read a number of amateur stargazer reports extolling Fremont Peak (near San Juan Bautista, CA). Due to the peaks altitude and relative isolation, seeing conditions are generally quite good (weather permitting, of course). As a result it appears to be the "goto" place for dedicated amateurs living, as I do, in the San Francisco Bay area.
So you'd think I'd of get up a head of steam and trek off to Fremont Peak wouldn't you? We'll hold on partner, I don't plan on running off anywhere too distant until I've exhausted my own local resources first...
I did get motivated enough, however, to broaden my explorations locally. So I decided to "head up into the mountains". To where all the haze that slides down into the San Lorenzo Valley and makes my BC Elementary School experiences so exasperating comes from.
With scope in hatchback, I headed west toward Big Basin State Park. Four miles outside town, I picked up China Grade running (more or less) north and up. Three miles, 97 potholes, a one lane bridge, and a downed tree later, China Grade dumped onto another road continuing north (again more or less). Not too far down that road, I found a nice little turn out facing toward an expansive southern horizon with decent views east and west as well. The peak of the ridge lay behind me to the north, but even it was low enough that I could easily make out Polaris about 10 degrees above the ridgeline.
After setting up the scope, it was still a little early to begin deepsky pursuits in earnest. So I took the opportunity to "characterize" the inside/outside focus behaviour of my scope. Using a descending Vega as the target star, the first thing I noticed was, you guessed it, tube currents. Since the currents would have little impact on characterization, I moved forward with testing:
Inside Focus Center Station:
Ideally de-focused star "envelopes" (diffraction rings) should be perfectly circular with the bulk of the light at the innermost ring and progressing outwards. Each subsequent ring should, in turn, be slightly less luminous, yet remain concentric with the next. Distances between each ring and its neighbors should be identical.
In my scope there are two variances from the above. First the brightest rings are the innermost and outermost. The second is that there is a slight elongation of the envelop to the left side of the eyepiece (when my back is positioned away from the diagonal). I attribute issue one to the fact that there is a 34% central obstruction (design of the scope). Issue two is the result of a slight mis-collimation.
Inside Focus Four Stations of the Cross:
By moving the defocused image around in the FOV (using the RA and declination controls), I evaluated field flatness. Inside focus you should see "moderate" elongation of the defocused image toward the center of the FOV. This in fact was what I saw during the evening's star test.
Outside Focus Center Station:
In a scope sourced with perfect optics, possessing excellent collimation and mechanical actions, the outside focus image should be identical to the inside focus image.
In my scope this is not the case. The issue is an elongation toward the bottom of the FOV. (This results in a "scrunching" of interference rings opposite the elongation.)
Inside Focus Four Stations of the Cross:
With the defocused image at the top of the FOV, the interference pattern looked like what it should look like in the center of the field. At left and right, the elongation extended away from the top of the field. I interpreted this to mean that the mechanicals in my scope cause the eyepiece to "droop" when the focuser is extended. This is something I have to look into correcting if I want to get the most out of my scope -- especially when it comes to the planets.
Sky Conditions:
With the above characterization finished, and as Lyra continued to sink to the west, I switched over to the Double Double. What I saw was a very poor split at 180X and a 12th magnitude come only visible with moderate aversion. The shift over to M57 gave a slightly different picture. There I was able to make out the 13.1 field star just north and east of the ring with extreme averted vision. (8 stars were seen in the Y-shaped "Chalice of the Ring" along with the 12.8 magnitude field star using moderate aversion). So transparency was demonstrably better than that seen at the BC Elementary School location.
To verify this I checked unaided visible stars in Cassiopeia. I could just make out 4.6 magnitude Iota directly. (A 5.4 magnitude star between Kappa and Beta could just be made out with moderately averted vision.)
Iota itself was a clean, if unstable, split at 180X. The 12th magnitude field star was visible averted at 50X and directly at 180X (with patience).
M56 Cygnus:
Given that, for the time being, my principle deepsky concern is globular clusters, I shifted over to M56. Using moderately averted sight, I was able to make out about a dozen stars in this 8th magnitude cluster. The stars were not consistently seen, they sort of scintillated in and out of view. (I suspect that 6.0 magnitude conditions are needed to really nail this one down.)
M2 Aquarius:
Given it's more southern declination, this globular had a brighter background setting than M56. It is also more compact and much brighter. I was able to make out about a half-dozen stars using the direct vision technique of "soft eyes".
NOTE: The soft eye technique involves lightly "meditating" on the core of the globular. After a while, and without any real effort one suddenly sees a "scintillation" of stars -- especially away from and encircling the core.
M15 Pegasus: This cluster is ideally positioned in the darkest third of the sky at this time. Using soft eyes I was able to see several dozen member stars at 180X. Again I noticed the lovely blue field star about 10 arc-minutes north of the cluster's limb.
First Lights:
M76 Planetary in Perseus:
Planetary Nebulae always give me some pause. It was years ago when I first found the Ring Nebula (in a 4" Dynascope at age 11). But planetaries generally seem to be a bit of a struggle (NGC 6826 in Cygnus was difficult and I have yet to find NGC 1535 in Eridanus). However tonight, I was able to pick up "The Little Dumbbell" quite quickly (once Phi Persi was located).
Under 12.4 LTM conditions (experienced tonight), the general shape of this planetary was only perceptible under moderate aversion. Direct examination revealed a diffuse glow with a length perhaps twice its width and a hint of a pinch at the middle. Using averted vision, it more clearly looks like a "lazy eight". The planetary's major axis runs southwest to northeast. The southeast component is perceptibly brighter and better defined. The planetary is about 2 arc-minutes long, 1 wide and roughly of the 11th magnitude. (The books say 11.5 -- but, if so, I wonder how Messier ever came to notice it.) Although M76 looks grey, but I had no trouble imagining a hint of blue.
M110 Elliptical Galaxy in Andromeda
Under the dark sky conditions of the new site, I decided to revisit M31 before moving on to M110. And for this I was well rewarded. Under averted vision, I saw flashes of intricate swirling detail -- spiral arm delineation -- and determined that some low surface brightness "nebulosity" did extend past the dark lane that truncates the northwestern flank of this huge galaxy. I also estimated that there must be fifty to one hundred field stars overlaying the galaxy itself. (Surely, all of them lie within our own galaxy -- but who knows, one of them could be a supernova!) To my eye there was no special concentration of stars that warranted an NGC206 (west of M32 on the galactic disk).
On to M110: This dwarf elliptical lies about half a degree northwest of the parent's core. In fact, I found that at 50X (35mm Ultrascopic), I could get some of M31, M32, and M110 in the same 1 degree FOV. Nowhere on M110 is the surface brightness nearly as bright as the core of M32 (it's sibling companion galaxy). However, the visible portion of M110 is much larger than that of M32. The main component of M110, in turn, is probably no brighter than regions of M31 (outside of the core). My notes say the elliptical runs north-south (with the bright region to the south). The northern region is a faint "haze" accompanied by a triangle of 10th magnitude field stars. Under averted vision, a sense of structure seemed to present itself. The structure surprised me by appearing slightly "spiralesque". It may very well prove that the northern region is nothing but "star haze", that the elliptical is actually oriented along a different axis, and that there are no spiral lanes present.
NOTE: After getting home I looked up M110 in Harrington's "Deep Sky". The book says "Northwest - Southeast" so I suspect the patchy nebulosity I saw was garden variety "star haze" -- the scourge of the Nebula Hunters.
I returned home around 9:30. On the way I stopped by BC Elementary School. As you might suspect there was no haze present and sky conditions were virtually identical to those seen at "China Ridge". I believe the expression is: "Go figure".
Star Party for One
Date: Saturday, December 16, 2000Went up to the Bonny Dune observing site. Gate was open when I arrived so I let myself in (about 5:00pm). Found no one else there but a kindly fellow doing some contract work for the property owner. We had a nice chat about things astronomical. (He had purchesed his wife a small telescope for her birthday a fews years past. She rarely used it.) I noticed that the lights were turned on on the runway and at the hangar. He arranged for the property owner's daughter to turn them off. I set up, turned on some Alan Parson's and began checking out my scope's optics. (I had some serious concerns about field flatness and "focuser droop".) The focus seemed quite stable. So I took a chance and simply removed the shim I had installed to support the old star diagonal. Amazingly, simply removing the shim eliminated the problem. The amount of elongation at the "four stations" was reduced. And the proper patterns could now be achieved for inside and outside focus.
Now I was eager to review objects seen previously.
However, high thin (cirrus?) clouds plagued the sky. By astronomical dusk, conditions were similar to those seen at China Ridge the night before (UTLM=4.6). Like China Ridge the sky was also unstable so the planets were a no show as well. Shortly after finishing my "review series", the high thin clouds started piling up. I did get a look at the core of galaxy M33 in Triangulum before breraking down, however. I need to revisit it next chance and do a full write up. The review series echoed everything seen the previous evening at China Ridge. M2 was not resolvable -- M15 was.
Let the Sky Decide for You
Date: Sunday, December 17, 2000The plan for today was to wait until the sun got behind the mountains and check the sky for cirrus accumulation. Based on that I was either going to do a backyard viewing session (featuring Jupiter and Saturn) or drive up to China Ridge and delve into some deepsky. By 5:00pm I had worked up a list of observations for the next few weeks, checked the sky, and found no evidence of "high thinnies". So I packed the hatchback and headed west and north.
Before setting up at my last location on China Ridge, I continued past the ridge road and drove several miles further up China Grade. The road eventually dumped out at Camp Cutter (a scout camp). Nothing especially promising caught my observing eye. Turned around, drove back four miles and resumed yesterdays perch on the ridge road.
By this time it was getting dark. As it turned out it never got as dark as I hoped for -- despite the lack of high thins (4.6 UTLM). Worse the sky was very unstable. Vega was a huge blur. Epsilon Lyrae was a pair of lesser blobs. Iota Cassiopia, unresolvable. (Couldn't even make out the wider 8th magnitude tertiary.) The 12th magnitude Iota field star was almost, but not quite, directly perceptible. (Based on the ULTM, I would say that this star is probably magnitude 12.1 or 12.2).
What all these conditions boiled down to was this:
Scratch any globular resolution checks, double stars, small planetary nebulae, or planet work. What remained were galaxies, nebulas, open clusters, and constellations.
Started with a check south to see what constellations I could make out above the next ridgeline. Fomalhaut (Alpha Pisces Austrinus) was easy (maybe 25 degrees above the horizon). Then I noticed a pair of reasonably bright stars a few degrees above the ridge. These turned out to be first magnitude Alpha and second magnitude Beta Grus! With certainly I could see to minus 50 degrees (southern) declination. (The stars seemed to have lost maybe 2 magnitudes due to atmospheric extinction.) Now the wait is on until next summer and Scorpio!
Next I took a quick peak at NGC6888. Again the Crescent Nebula is a definite maybe. (This thing would be in the bag except for all the damnable star glow seen everywhere -- even without the high thinnies this particular evening.)
Then on to the Eastern (NGC6992) and Western (NGC6960) Veil Nebulae. Both were visible -- even without the OIII filter.
Now I was ready for a new First Light: NGC7789 was on my list. I was intrigued by the fact that it is reputed to be one of the denser open clusters. It is easily located about one degree south-southwest of Rho Cassiopiae. Unlike many clusters (in this rich Milky Way region) -- it was easy to identify. The thing is very compact -- almost a poor man's globular! Stars blend from about the 8th magnitude into a general star haze of 13th and 14th magnitude members. Several hundred stars are perceptible. The bulk are distributed almost "concentrically" in the northern more "globular" component. Fewer stars are visible in the southern "semi-pipe stem" section. A loose jet of 10th and 11th magnitude stars arc from the southern component to the east ("above") the northern globular section. The overall dimension of the cluster is roughly 10X20 arc-minutes. The general impression is that of a steller "dumbbell" (or a well-filled bra -- if you prefer.) I predict that NGC7789 will become very popular with the Star Party crowd. 100X in reasonably dark skies should do it. Small refractors should show it very nicely and give the experience of a bright globular as though resolved in a larger scope.
Since I was in the region, I decided to round out my experience with M31 and companion galaxies. I had already (briefly) explored M31, M32, and M110. Now NGC185 and NGC147 beckoned. I started with 185. To find it, I positioned Omicron Cassiopia in the center of the finder. (Omicron is roughly halfway between Alpha Cass and the core of M31. It's the brightest of three stars that form a line in the finderscope pointing toward M31.) With Omicron in the main scope field, I shifted it east one degree and slightly to the south. As I did so, I caught a circular "blob" of nebulosity with averted sight. Once detected, I was able to vision it directly. All I could honestly make out was a roughly 7X7 arc-minute "core" which looked suspiciously like a distant, unresolvable, low surface brightness globular cluster. (There were also hints of an elliptical shape -- but not nearly so obvious.) I spent several minutes contemplating this circular smudge at 50X, then moved on to NGC147.
Another slight shift south and another degree west and -- nothing. that is nothing definitive. Just a diffuse, larger smudge of vague luminosity amidst some 10th magnitude and dimmer field stars -- with the characteristic "star glow" I have come to know so well. (No my optics aren't particular dirty -- this is probably an atmospheric problem -- or a general Milky Way condition.) What makes this M31 attendant so hard to identify is the lack of a definite core. Needless to say, I'll have to revisit both these objects under darker conditions.
Now, why not finish the M31 tour?
Started with the eye, Yah, there it is. A fuzzy blotch on a line extended past Mu from Beta Andromedae. Quick look through my 7X35mm binoculars. Wow, this thing is LARGE and BRIGHT! Never noticed how present the arms are at 50X in the main scope... 12?
Center the scope on the core, turn on the clock drive, try to keep M32 and a little bit of M110 in view to get a sense of general arrangement. M32: Sharp, bright, pointlike core with rapidly diminishing star-haze about 5 arc-minutes in diameter. This companion galaxy is easy bright and positioned as it is about 25 arc-minutes south and slightly east of M31 core. It looks like a highly condensed globular cluster unresolvable to the eye.. M110: Much larger, more diffuse, elliptical of diaphanously hazy light 35 arc-minutes north and west of M31 core. Easily found with direct vision. Directly viewable with details suggested to averted sight. Overall, much dimmer than M31 but brighter and more extended than NGC185.
The clock drive allowed me to really relax and use "soft-eyes" to make out detail. Again I noticed that the eastern wing of the galaxy is fainter than the west. The core itself seems to extend into the west wing. To the east it is truncated by dark matter. Several dark lanes were perceptible between M31 and M110. A general "spiralesque" sense was hinted at (with averted vision). Nothing that could be detailed, however. A number of stars arrayed themselves across the western wing. I made no effort to scan out to the locale of NGC206 (about a degree or so from the core). But I will take this up next opportunity.
On the off chance that seeing might have improved, I took a quick look at Jupiter: Two bands, vague irregularities along their edge. No doubling up. 4 moons layed out rather nicely however...
Broke down the scope and headed home. Once I arrived, I re-assembled and checked the seeing from the backyard. Again Jumping Jupiter: Two bands, vague irregularities, a hint of belt doubling. Decided to simply watch for awhile with clock drive, 210X, and blue filter. Again the sense of seeing a reflection in a dark well -- but the water was agitated. Not a boiling -- just a skidishness. Occasionally a little more detail would flash out -- then focus was lost and the image became vague again. This "jumpiness" doesn't really account for the lack of detail. In addition to the occasional first order disturbances, there must also be a more constant second order (high frequency)turbulence to cause that -- or my scope would have to be whacked out of alignment...
Put the scope away, came in and wrote up my notes...
Jupiter and Saturn Redux
Date: Monday, December 18, 2000There's no problem with the scope...
This evening I configured for the planets. 3X barlow, 25mm Plossl, and 15mm Ultrascopic (210 and 360X).
Checked the sky around 5:45. Couldn't split Epsilon. Didn't bother check Iota. Left the scope setup, took care of a few things then came back out to view the planets around 7:45pm. Started with Saturn at 210X. Like last night the image leaped about in the FOV. Unlike last night, I could bring the planet into focus. Although sharpness varied with occasional high frequency turbulence, the image distortion seen last night had abated. Sky transparency was not good (as usual) from the backyard . (Couldn't directly view Kappa Cassiopeia -- but slight aversion showed it.)
In fact, I was able to use both 210 and 360 throughout the Saturn checks. This is what I found:
Something new: For an instant during peak sky stability and transparency I saw extensive irregularity along the northern edge (equator side) of the SEB. I would have missed this without the clock drive running.
Something Old: No view of the Encke Gap.
By the time I shifted to Jupiter, the sky was much more stable than at the beginning of the Saturn checks (about 45 minutes earlier). There was however, some residual "high frequency" turbulence but not a whole lot. Conditions were ideal for some breakthroughs.
Jupiter:
I installed the medium blue filter into the 25mm ep barrel. The first look told me that something had changed. Contrast was visibly better. (Perhaps straightening up the intra/extra focal problem really had an impact.) On noticing the improved contrast, I knew I would have to spend some serious time developing my observing technique. "Soft eyes" just might be the answer. Here's the Jupiter list that came out of it:
NOTE on soft eye viewing: I found that in addition to being in a state of relaxed alertness, my eyes were kind of "looking through" or "looking past" the body of the planet -- even though I was directing my observing eye at the planets center. This is why "soft eyes" is different from "averted vision".
... And so on Ad Infinitem.
Date: Wednesday, December 20, 2000Took the scope out around 9:00pm this evening to follow up and last evening's planetary observations. Viewed both Saturn and Jupiter. Saturn displayed such a finely chiseled look that I took out the 9mm Plossl to augment the 25mm and 3X barlow.
Saturn took 600X very nicely this evening. No new features were seen on the globe or rings however. Didn't get a glimpse of SEB edge irregularities (hinted at last night). However, I did make a few "measurements" of the width of the three components of the ring system.
At 600X, the relative widths of the A, B, and C ring components could be fairly reliably estimated. Ring A appears to be about 2/5 th the overall crossectional width of the complete ring. Ring B is slightly wider, and Ring C takes up the balance.
In making these estimates, I assumed that the Crepe Ring (Ring C) begins just where Ring B begins to lose density. I also used Cassini's Division as the separator between Ring A and Ring B. Again the few and brief flashes of the Encke Gap that I made out this evening showed that it is positioned about 2/3rds the way out towards the ring system frontier (from Cassini).
While viewing at 600X I also got a "close" look at the ring presentation. In so doing I am now able to definitively say that the southern ring no longer extends past the south polar region of the planet. In fact it is now detectably below that point. So things are starting to close up. Get your ring views while there hot!
Oh yes, sky conditions: Tonight was unusually dark (for my backyard observing station). Iota Cassiopia could be made out with very slightly averted vision. In the telescope, Iota's 12th magnitude field star was just directly visible. The Iota triple could be cleanly split at 120X. Unlike many planet sessions, the sky was unusually transparent. However, planet image's were slightly "jumpy" with "twitch" in the focus. No "boiling" was seen however.
The unusally dark skies did give me an opportunity to see a great many more "stars" in Saturn's attendence. In fact 8 bodies were seen that could be satellites (ie located on the imagined ring plane in 3 dimensional space.) The configuration resembled the following:
.9 .11 .8 .11 O .12 .10 .9 .10
NOTE: Numbers are suggestive of visual magnitude. 12th magnitude object was only directly visible at 600X. (Occasional glimpses were possible at 210X however. Based on a NASA simulation program, I have determined that six of the above bodies are actual satellites Titan, Rhea, Tethys, Dione, Iapetus, and Enceladus. The simulation did not name the satellites.
Another factor at work tonight was the minimal "light scatter" in the eyepiece. This may be attributed to the better than average humidity. (Certainly not dry out -- but definitely better than anything I have experienced in my backyard in quite a while.)
Jupiter:
My main reason for looking at Jupiter this evening (do I really need a reason?) was to determine whether or not I could get a steady view of the kind of equatorial band detail seen night.
The answer to this question is no. I could not get a "steady" view of equatorial features, but I did get occasional "extended flashes". Enough to convince me that there is a whole new level of detail possible at the very limits of my ability to "see" with this scope. In fact, when such flashes did occur it seemed as though fine detail "exploded" into view all over the planet. (Some even in the polar regions.)
Another factor I noticed. Jupiter is not nearly as "magnification friendly" as Saturn. To see extended textures and features on Jupiter required that I use no more than 360X. (In fact 210X gave more consistent results.)
Also during tonight's observation, I noticed what appeared to be a "detached piece" of the NEB floating in the equatorial band. This is a first. (This piece was not a transiting satellite shadow. When this occurs, the contrast is so intense that it seems like a black hole is burrowing through the body of the planet along the equator.)
A final note. The observations of today and yesterday occured with both planets high in the sky. Earlier in the season, most viewing occured while both planets were in the ascending third of the sky, I had less experience viewing them, and my scope was not entirely healthy.
Observum Interruptus
Date: Friday, December 22, 2000By 5:30 this evening the sky was looking friendly towards deepsky work. So after taking care of a few things and having dinner, I packed the scope up to the school around 7:45. By this time Lyra and Cygnus was too low to view above the adjacent rooftop. A check of Cassiopia showed Iota barely direct. At 120X it could be cleanly split and its 12th magnitude field star was again, just barely directly visible. I found it interesting that both Iota and the field star were both just barely visible (one with the naked eye and the other through the 5.5" clear apertured scope). This will make a useful reference in the future.
My immediate goal was to track down galaxy M33 in Triangulum. One of the more difficult Messier objects, this nearby member of the local group appears about the size of the moon -- but at magnitude 5.6, it has rather low surface brightness. According to the books, it usually requires a dark night to locate and is often more easily seen in the finderscope or a good pair of binoculars than in the main scope. As it turned out, by the time I had oriented to the general location of the galaxy in the sky (roughly 1/3 the angular distance between Alpha Triangulum and Beta Andromedae), a passersby interrupted me and I broke off planned observations to show him (Bill) Jupiter and Saturn.
As it turned out, this was not such a bad thing. One of Jupiter's satellites was rapidly approaching its eastern limb. We were both keenly interested in finding out whether the satellite would remain visible when it passed in front of the globe. Twenty minutes later we found out. The satellite just happened to engage the limb along the southern frontier of the SEB. The material in that area is quite dark. The satellite remained visible almost a quarter way across the globe. It remained visible for about an hour. Atmospheric transparency then began to degrade. The usual late evening haze moved down the slopes from the mountain ridges west of the school. I could no longer make out Kappa Cassiopeia with direct vision. The planet's features lost a little contrast several minutes before it's shadow broke the eastern limb, the satellite disappeared.
Long before this point, Bill had left. I spent the next hour or so more or less continuously watching the black pinpoint cut a direct line across the planet. At no time did I get a definitive view of the satellite's bright body -- only it's shadow, patiently progressing along the brown highway of the SEB. I continued observing, until the shadow transitioned across Jupiter's central meridian. As I observed, I noticed a general improvement in the stability and focus of the planet's image. Both the NTB and a section of the STB were now visible. (In fact the STB cut a short segment about 1/3rd the width of the planet's body centered just above the transiting disc.) A clot of dark material on the NEB also paralleled the shadow. Before this clot was an even larger projection of material into the equatorial band (EB). Every once in a while (when my eyes fully relaxed and focus sharpened), I detected the thin, faint, white belt that bisects the EB. Occasionally, I would catch the soft white "dove's feet" p attern on the EB as well.
About this time Orion had risen to the middle third of the sky. I decided to view the trapezium (within M42) in hopes of detecting a fifth come. With the 25mm ULtrascopic + 3x configured barlow in place I inspected the trapezium at 210X. Then again at 360X (using the 15mm Ultrascopic). Even with an unaided threshold limiting magnitude (ULTM) of 4.0, the dimmest 7.9 trapezium member was easy. But it will definitely take darker conditions than this to reveal a fifth (and possibly 6th) component.
I turned the scope on Saturn. This was done to "round up the usual suspects". Saturn's moons are in some ways more interesting than Jupiter's. True the Galileans all show tiny discs (even at 210X) and they can do exciting things (like transit across the primary), but they are not as enigmatic as Saturn's. Nor are they as impacted by observing conditions. So the challenge of Saturn's moons boils down to "How many star-like points on th ring-plane can be seen?". "Which of the star-like points are satellites?" And finally "Which satellite is which?"
Of Saturn's satellites, five are easily seen (in a six inch scope) and among them, Titan is the most easily identified. The other four (Rhea, Tethys, Dione, Iapetus) are more difficult to identify. (Iapetus is variable in magnitude and can sometime's prove difficult even in a six inch). To identify these moons you need to get an ephemeris (or go on the web and find the current configuration). Here is the configuration of star-like attendants de jour:
.100 .90 O .110 .120 .80 .90
NOTE: Numbers are suggestive of visual magnitude. 12th magnitude object was only visible at 360X averted.
Now it was time to return to Jupiter and catch the emergence of the satellite from the western limb of the planet. So turning the scope back on Jupiter I found I was a wee bit late. The satellite was already well clear of the limb. It's shadow, about 1/4 of the disc (10-12 arc-seconds) behind, continued to make way against the southern frontier of the SEB.
By this time it was getting late and cold. Just as I started breaking down, the second visitor of the evening stopped by (Kerry). Like most first time viewers, she was simply amazed at the views of Jupiter and (especially) Saturn.
Confidence Gained
Date: Saturday, December 23, 2000Son Eric and I drove up to China Ridge this evening. We arrived just in time to watch the last few golden orange clouds of dusk hang over the horizon to the west. High sheets of thin clouds cut directly overhead. To the east, clouds thickened to the point of opacity. The northwest, however, was relatively free of obscuration. Vega soon rayed into view. After scope assembly, Eric received a little demonstration of interpreting intra/extra focal interference patterns (using Vega as a target). Based on irregular spacing of two concentric rings in the extra-focal diffraction pattern, I explained that the scope was slightly undercorrected.
We then went on to view the Double-Double. (Clean split at 120X.) I had him look for the 10th and 12th magnitude comes. (The 10th magnitude star was easy. while the 12th magnitude star required mild averted sight.) A checked of Kappa and Iota Cassiopiae showed that 4.2 magnitude Kappa could be seen direct and 4.6 magnitude Iota indirect. I explained that the 5.5 inch unobstructed scope reveals stars 7.5 magnitudes dimmer than what can be seen without it. I also mentioned how we needed to be able to see down to the 12th magnitude directly to have much success locating "faint fuzzies".
As the sky darkened, we peeked at the Ring Nebula. I was pleasantly surprised that both Eric and I could occasionally catch the 13.1 magnitude field star (indirectly). Another quick check of Cassiopiae and we agreed that Iota was now just barely perceptible (direct). We were pretty sure that now (occasional clouds notwithstanding) we could see (telescopically) down to magnitude 12.1. To confirm, we used 120X to split Iota and got a direct view of the 12th magnitude field star. So, but for the shifting, intermittent cloud streams above us, we could now get down to some "deepsky".
To begin: NGC6888 (The Crescent Nebula in Cygnus). Again inconclusive. We'll need a darker night (5.5ULTM?) before any claims can be made here. Moving on, I showed Eric the Andromeda Galaxy Family: M31, M32, M110, NGC185 and NGC147.
NGC147 is the most difficult member of the clan. Listed at magnitude 9.3, its surface brightness is visibly lower than its nearby sibling (NGC185). NGC185 can be found quite easily in 12.0 conditions, but NGC147 requires more persistence and a subtler sense of what to look for. In fact, I missed 147 on my first attempt and only concluded that we had turned it up this evening after verifying that the nebulosity observed was not associated with field stars. (which cause star haze under less than perfect viewing conditions).
NGC147 is positioned near a "kite shaped" asterism of 10th and 11th magnitude stars. These take up about a third of the 1 degree FOV (seen using the 50X 35mm Ultrascopic ep). The asterism is oriented roughly N-S. The elongated nebulosity skirts the western diagonal. 147 is roughly 15 X 10 arc-minutes in size and -- like the kite asterism -- orients along the NS axis. It's basic shape is detectable but only using averted vision. (Although it's presence can be established directly under 12.1 conditions). Unlike NGC185, it gives no special sense of having a "core". This probably explains why it so difficult to locate.
Interestingly enough, I felt somewhat exhilerated finding this "difficult" object. It has helped me better appreciate those amateurs who, possessing years of experience, and large scopes, go after 13th and 14th magnitude galaxies with fearless enthusiasm...
My other goal for the evening was to catch "first light" from M33 in Triangulum. Locating Triangulum for the first time was none too easy. Any three stars will form a triangle (if not a line, an arc or such). The key to locating this particular triangle was to follow the arrowhead formed by Cassiopiae's "lesser V" to the south. Cross over the outstretched hand of Perseus and Andromeda in its entire. Then find the brightest (southernmost) star of the first small triangle you encounter and lay a line back toward Beta Andromedae (generally in the direction of the Great Square of Pegasus). By sweeping this line with the finderscope, a fairly bright hazy patch about the size of the moon will be seem roughly 1/3rd the way between the two stars. Center the crosshairs and switch to the main tube.
Several questions came to mind while viewing this object, (the core), of M33. One is: "Why isn't it larger?" You'd expect from the finder to see something about half the size of the 1 degree (50X) FOV. In fact, my first estimate of its size was roughly 7 X 7 arc-minutes. But this proved to be the brightest, central core of the galaxy. After some contemplation, I arrived at a later estimate of 30 X 20 arc-minutes. (The core extension seems to be somewhat truncated to the west, while the east is globular, and the north-south axis elongated.)
The next question I had was "Which direction are the spiral arms?" Using relaxed vision, I could easily imagine the spiral arms going both north-south and east-west. In addition, there was so much "glow" wherever I looked that I couldn't get any particular sense of orientation at all (other than the slight core elongation). So I just wrote up what I could and moved on..
As it turns out... M33 is a huge face on spiral. It has more arms than Hakini, and enough alternating light and dark nebulosity to spawn a handful of additional NGC references and a slew of IC designations to boot. The dark areas I observed around the core are real. Much of the "star haze" seen is equally real. This first observation "focused" only on it's nucleus. A nucleus which does, indeed, orient south to north.
With Orion ascending in the southeast, I made a quick check of the trapezium at 180X. There was no conclusive evidence of additional stars within, or near, the four easily revealed components...
I followed this with a quick look at M78. The main nebulosity was quite apparent (engulfing as it does the two stars of the kingfisher's beak). The two talon stars also showed nebulosity as well -- but by this time "high thinnees" were swooping down into the scene. The question as to whether a six inch instrument can reveal the NGC2071 reflecting nebulosity remains unanswered -- for the time being.
Establishing Deepsky Momentum
Date: Monday, December 25, 2000Son Christopher graced me with his presence at this evening's China Ridge observing session. He, like Eric, found the expansive view to the south and west quite breathtaking. Since se arrived well after sunset, he missed the luminous clouds to the southwest. Before we set up the scope I oriented him to the main constellations and the Milky Way.. Lyra, Cygnus, Pegasus, Andromeda, Cassiopeia, Perseus, and Auriga were all pointed out. The stars Vega, Deneb and Cappella were named as well as Polaris.
We teamed up on assembling the telescope. Chris used the declination spotter to orient the equatorial mount to the pole star. (I don't usually bother with this, but Chris seemed to think it was important.) Once the scope was mounted, diagonal inserted, all lens caps removed, and 15mm 120X ep installed, we turned it on Vega to check collimation. Intra/extra focal diffraction rings were more or less centered but the pattern showed a great deal of atmospheric turbulence. Poor stability was later confirmed when resolution of the main pair of Iota Cassiopeia proved impossible (although the 12th magnitude field star could be viewed direct). Iota itself was visible directly early on. (Later on 4.9 magnitude Chi Cassiopeia could also be barely seen directly.) Altogether the night would be best dedicated to showing Chris around and possibly tracking down a few nebulae.
We started with M57 (dark core hard to make out with Lyra so low and the sky so turbulent). Then M56 (again very low and turbulent -- no stellar resolution possible.) M15 (dozens of components using averted vision). M31 (with core centered in field spiral arms exiting the 35mm, 1 degree 50X FOV in both directions. M32 (bright central core obvious, rapid diffusion into space otherwise). M110 ( easily seen with direct sight). NGC185 (tougher than 110 but still directly viewable). NGC147 (I could see it slightly averted to direct, Chris came up empty.)
NGC7789 (a dim hazy patch in the finderscope, Chris was impressed with the "hundreds of stars" in the main tube). As it got darker I inspected NGC 6888 in Cygnus (so close but no cookie -- next autumn maybe). After NGC281 ("First Light" reflecting nebula in Cassiopeia), Chris was even more impressed by the "Double Cluster" between Cassiopeia and Perseus. Finally before breaking down (around 10pm) we spent a bit of time ooo-ing and aaa-ing over M42 in Orion. Now on to "First Lights"...
First Lights:
NGC281 forms the eastern apex of a more or less equilateral triangle with Alpha and Eta Cassiopeia. So it is very easy to center the finderscope on it. The finderscope itself hints at a small patch of light in a none too rich Milky Way field. The 50X view through the main scope however, is less re-assuring. To be sure, I could make out a subtle "sheen" of light. However, it proved very difficult to get a sense of it's basic shape or sky-orientation -- even using averted vision or an OIII filter. My best guess is that NGC281 is somewhat elongated with a north-northeast to south-southwest orientation. A 9.5 magnitude bluish-white field star lies to its west about halfway along it's (very roughly) 18 X 12 arc-minute length. The eastern flank seems to be bordered by a parallel lane of dark nebulosity. I'll definitely have to revisit this object over the years to determine if there is more to made out as my eye ripens with experience.
NGC246 is a rather large planetary nebula forming the (slightly distended) southern apex of a triangle with Theta1 and Theta2 Ceti. In searching for this object, I immediately came across a fuzzy patch of 11th and 12th magnitude stars that seemed shrouded in nebulosity. Since I don't usually read much about an object before looking for it, I was unaware that this is precisely what you'd expect to see in a small scope. Because I didn't find what I expected, I looked the object up (while on site) in Philip Harrington's "The Deep Sky": "A dim ring of grayish material that appears to encompass several faint stars."
In fact, at 120X (15mm Ultrascopic), I could make out six stars in the original small cluster first noticed. At this higher magnification, the planetary was seen to actually enshroud only the northernmost triangle of stars. In appearance it is a vaguely elongated outer shell of diffuse light probably 4 arc-minutes in length and 3 arc-minutes in width. Unlike M57 for instance, neither the central breech or the outer shell were particularly well defined.
One thing I noticed in observing this portion of the sky: It sure was "brighter" than directly overhead. You definitely lose at least 1 magnitude when you are within 40 degrees of the southern horizon (as this planetary was).
Having found one new planetary, I was ready for another. So I resumed the quest for NGC1535 in Eridanus that I started at the Santa Cruz Astronomy Club star party earlier in the season. On that occasion, I attempted to find the planetary by just generally pointing the scope about 1/5th the distance between Gamma Eridanus and Rigel, then sweeping the general location. Though a decent method when you know what you're looking for, it's not practicable when you don't (since there are too many variables to psychologically contend with). So after ten minutes of sweeping around using this method, I tried a variation on Harrington's: Locate Omicron1 and Omicron2 Eridani in the finder. Drop down about 2 1/2 degrees south to a 6th magnitude star. Center the 6th magnitude star in the main tube. Continue south another 2 and 1/2 degrees. Look for a fuzzy blue out of focus star in the 1 degree FOV.
My notes say "a classic planetary nebula with central star. Green-blue in color. Bright center rolling off in intensity at the edges. Coloration obvious. Size around 1/3rd arc-minute. Use 180X." In fact this planetary is the brighter, twin brother of NGC6826 in Cygnus.
On our way to admiring M42, I took a quick look at M78 in Orion. Nebulosity apparent in both talons of the "Kingfisher" asterism. Is this real nebulosity or just star haze? (The nebulosity associated with the Kingfisher's beak is obvious while that at the talons is not...) Is there a theme here? What's real and what's hazorex?
M42:
There is no way to exhaust this subject. Here are my field notes from tonight: "Nice study in black and white with a hint of pinkish gray at the fringes. Dark nebula oriented northeast to southwest. Brightest region to west. Dark region to east looks like an eagle with outstretched wings. Tight formation of 4 stars (the trapezium) above its head. Pinkish gray along the top of the southern wing. Overall dimensions perhaps 40 X 30 arc-minutes. Bright nebulosity extends with diminishing surface brightness to the west. Traces of bright nebulosity along the northern leg of the eagle. Lone, dim 12th magnitude star between the eagles legs. Two brighter stars (of unequal brightness) tip the eagles talons. Short dark lane of nebulosity above the eagle's crown cutting through the bright western nebulosity."
Pack it up, head home. A successful evening of deepsky introductions and orienteering.
Fruits of Perseverence
Date: Thursday, December 28, 2000With the holiday familial's behind me, I took the scope up to China Ridge. My hope is that, sooner or later, I'd begin to see the kind of 5.5 and 6.0 ULTM nights that would allow me to flood the FOV with faint fuzzies. Like all previous evenings, that hope proved unfulfilled. Conditions were very stable, however, (easy, clean split of Iota Cassiopeia) even if not particularly dark (at its best around 4.8). The air was also relatively warm and dry -- very much like a late summer evening. High thin clouds intermittently flowed in from the south (off Monterey Bay). By 11:00 pm the sky was dominated by thin clouds and I knocked off. But not before tracking down three new "First Light" planetary nebulae and (almost) conclusively capturing mental pictures of NGC6888 -- the Crescent Nebula -- in Cygnus.
Even as the Northern Cross sank into the final third of the sky, I felt that the dry atmospheric conditions of this particular evening would prove useful in mitigating the star glow that complicates the "Quest for the Crescent". Once minimum "twelve-oh" conditions were met (based on direct perception of Iota Cassiopia's 12th magnitude field star), I dedicated about 30 minutes (with clock drive running) to inspecting the "W asterism" at 70X using the OIII filter. As I did so, I compared glow around stars associated with the Crescent with those of the Crescent itself. During this check, I made every effort to both see and imagine interconnecting nebulosity between the various like-brightness field stars. I found that, in every instance, I could imagine such nebulosity. However, these "imaginings" were not possessed of the same degree of "reality" associated with Crescent Nebula stars themselves. As a result, I've now concluded that I have, in fact, been seeing portions of the Crescent Nebula all along.
That portion of NGC6888 accessible to a 150mm telescope is found in a rich field of Milky Way stars roughly three degrees southwest of Gamma Cygni. The nebula forms a broken "C" oriented along an east-west axis. The visible portion of the nebula begins at a 12th magnitude star (at the peak of the keystone part of the W asterism) then circles around (southeast) to a 9th magnitude star. Nebulosity then concludes at a 9.5 magnitude star west of the original 12th magnitude component. The thickest portions of the nebula are to the southwest -- especially adjacent to and including the southern 9th magnitude star. The full perception of the nebula is just visible using averted vision (under the 4.5 ULTM conditions experienced tonight). The C is roughly 10 arc-minutes in height and 6 in width. Its overall surface brightness is in the order of the 12th magnitude. This low luminosity, plus light scatter from associated 9th and 10th magnitude stars, accounts for its relative difficulty in detection.
As for this evening's "First Lights", I selected three planetary nebulae: NGC40 (Cepheus), NGC7662 (Andromeda) and NGC2022 (Orion). Of the three, NGC7662 (magnitude 9.2) was most easily spotted and 2022 (magnitude 12.4) was the most challenging. At magnitude 10.7, NGC40 is intermediate in difficulty and is also the largest of the three (37 arc-seconds). (The others are half this size.) Since initial search is easiest using the 1 degree FOV 50X 35mm ep, each of these objects could only be noticed as "diffuse stars" in the eyepiece. Once located, all three required 180X to get a sense of structure. In the case of the two sub-20 arc-second planetaries, it might have proven advantageous to run the magnification up to 360X, but I elected not to break out the 15mm / 3X barlow lens combination required to do this.
NGC40 was a moderate challenge to locate. It's found in a rather barren locale and at a telescope position awkward to manipulate an equatorial mount to. My initial plan was to simply point the main scope about 1/3rd the distance between Gamma Cephi and Gamma Cassiopeia. After several minutes of fruitless, and ever-more increasing wayword searching, I decided to be more scientific. On star charts, I noticed a wide optical double consisting of two sixth magnitude stars about 5 degrees north and east of the planetary. I also noticed a sole 6th magnitude star 3 degrees south of the double. The 6th magnitude star was also 3 degrees east of the planetary. Locating the double was easy in the finderscope. Slew the declination axis swung the 6th magnitude solitary into position, a couple of rotations of the right ascension knob and there she was: An 11th magnitude central star surrounded by a diffuse gray disc.
The view at 180X did little to reveal additional details. The gray disk remained diffuse at the edges. Averted vision hinted at something like a gap between the central sun and the expanding shell of nebulosity. The planetary formed a tight triangle with 2 9th magnitude field stars. These, in turn, were separated by a distance of about 5 arc-minutes. A 12th magnitude star could also be seen at a distance of about 45 arc-seconds from the primary. The nebula was clearly less than a single arc-minute in diameter and did not even hint at any color other than gray.
I was able to use a modified version of the usual search method to find NGC7662. Star charts show that it is within the same 1 degree FOV as a 6th magnitude star between Iota and Omicron Andromedae. Pop in the 50X ep, center the finderscope on the marker star and voila -- look for something fuzzy, small, and relatively bright (magnitude 9.2) to the southwest.
Bright is right! This baby is white -- not gray -- with a tint of pale blue added for freshness. The annulus of this more or less circular planetary is definitely brighter to the inside and darker to the outside. There is no indication of a central star -- but I kept seeing a star-like point popping into my averted vision within the annulus but nowhere near its barely perceptible darker core. The ring appeared to be slightly brighter along the northwest to southeast axis. The off-axis star is positioned to the southeast.
I held little hope for finding NGC2022. Under normal "dark sky" conditions, the scope seems to run out of breath around magnitude 12. And here I was trying to locate a 12.4 mag object well down from the zenith in the direction of the Santa Cruz light dome!
And locate it I did -- about 1/3rd the distance between Gamma Orionus and Betelgeuse using the "point in general direction and search" method. As I searched I expected to catch only the vaguest intimations of a small, diffuse, grayish light at the limits of averted vision. What I actually found was a small, diffuse, ghostly gray fuzziness at the limits of direct vision. Inspection at 180X (using averted vision) showed a faintly green-grey disk. The disk showed no directly perceptible frontier. However, it may have been slightly brighter to the east. This planetary lacks any hint of a central sun. It is positioned between two twelth magnitude field stars about 3 arc-minutes apart. Two other stars, one (the further) 9th magnitude and the other of the 10th magnitude point in the general location of the nebula in the FOV.
This was a good find and certainly helps to bolster my "deepsky" orienteering confidence -- along with the ability to actually make out difficult objects in the FOV.
Mystery at Sea
Date: Friday, December 29, 2000Drove out to China Ridge. Found that by the time I arrived that clouds had moved in to dominate most of the sky. The sunset was glorious with splashes of yellow, orange, pinks and reds, descending down to the horizon. Wouldn't it be wonderful if we could see deepsky nebulation like this?
Noticed that I could see the Pacific Ocean to the southwest. Saw a "burning light" floating on the ocean off shore. Took out the binoculars for a closer look but couldn't really identify the source. Packed up the binoculars and decided to drive back home via Big Basin State Park. Thought I'd keep an eye to other observing sites along the way. Hoped that by the time I got home the sky would clear up and I could set up at BC Elementary School.
During the drive I noticed two other potential viewing sites not too far down the road. Didn't appear, however, to be any improvements over the one I had just left. Arrived at the school 30 minutes later. No sign of improvement. Got home and setup the scope for planetary observation (25mm and 3X barlow). Decided to wait until the planets were near the meridian before actually getting started.
Went out around 9:30. Sky transparency was still variable. Stability likewise but adequate. Didn't spend much time on Saturn. Moved on to Jupiter for an extended session. Decided to develop my left eye's observing skills. Noticed that the point of focus varied for my two eyes. Certainly the right eye was more skilled at observing detail. It also lacks the central fovea astigmatism that afflicts my left eye. Right eye could make out all the usual details on Jupiter (the STB however was not visible this evening while the SEB was clearly split). The left eye could not quite make out the NTB. I did notice however, that the left eye was seeing more than in previous experiments along this line. Astigmatism also seemed to have improved. Is it possible that observational astronomy can actually heal the eyes?
Southern Sky Deep Sky Challenge
Date: Saturday, December 30, 2000Eric joined me for this evening's expedition to the Ridge. He brought along a clutch of CDs for entertainment. Otherwise I'm sure he would have been less than fully engaged as I went about my observation plan.
That plan was to complete an initial survey of noteworthy deepsky objects between Right Ascension 0 and 1 hours, and Declination -45 to +90 degrees. Of course to finish up this project, I had to find the most difficult objects in the series. These included galaxies NGC55, NGC253, and M74, along with globular cluster NGC288 and make an attempt on star cloud NGC206 in M31.
We arrived on site and had the telescope setup by 6:30PM. Eric performed the colimation test using Vega (low to the northwest). The check showed the standard intra/extra focal pattern. Vega's image was quite turbulent. Several diffraction rings could be seen, however, within the turbulence. The double-double was a very dirty near-split. Surprisingly Iota Cassiopeia was nicely split and the 12th magnitude field star could be held by direct vision. It was just possible to barely hold the 5.4 magnitude star between Kappa and Beta Cass. Several caveats however. The moon was up throughout the entire viewing session and displayed about a 25 percent disk. High clouds moved in and out -- especially to the south where my targets lie. However, by the time we left, the moon was behind a tree and the clouds had drifted off. We finally had a 5.5 night -- and I had to abandon it -- having accomplished my goals and not wanting to tax Eric's patience...
Once Iota was checked, moved on to view NGC6888. The hope here was to fully validate the previous evening's conclusions. No validation was forthcoming. The Quest for the Crescent Lives! At 50X, basically saw what was seen last night. Diffuse nebulosity at the limits of star haze taking the required "imagined" shape. At 120X less of the haze -- and less of the nebulae was present. However, a handful of 13th magnitude stars were visible within the keystone asterism that were not even hinted at last night. Surely a dark sky reveals entirely new lights!
After ten or twenty minutes of inspecting 6888 (35mm:50X, 25mm with OIII filter: 70X and 15mm 120X) I took the plunge and decided to try my hand at finding NGC55 (RA: 0 hr 14.9 minutes, Declination 39 degrees 11 minutes, Magnitude: 8.2). As with the 12.4 magnitude planetary NGC 2022 two evenings previous, I really didn't expect much success. (I calculated that the surface brightness of this galaxy -- based on its size and atmospheric extinction would be in the range of 12.5 - 13.)
First challenge: Find the Phoenix. This was only possible using binoculars. Due to low clouds near the horizon and general atmospheric extinction, not a single star was visible to the unaided eye. (Even though the brightest star in Phoenix is of the 2nd magnitude.) Here's where binoculars played a crucial role. Guessing that Phoenix would be just west of the southern horizon around 7pm, I familiarized myself with its layout then scanned the low haze in that general direction with binoculars. As it turned out, this worked rather nicely. With Alpha and Kappa identified, I looked for a fifth magnitude star 3 degrees north of Alpha. Triangulation on Alpha and the 5th mag star allowed me to point the main scope in the locale of NGC55. A few "lissoujoux" search patterns and I detected a hazy elongated patch of slightly brighter gray in the murky soup of darker gray that passes for "space" at minus 40 degrees RA.
Using averted vision, determined that the elongated patch was maybe 15 arc-minutes long by 5 arc-minutes wide. It is oriented along an east-west axis. The "brighter core" of this galaxy spills rather symmetrically outward into the arms and then off into space. Under the conditions experienced, there is little else to report concerning this object other than the fact that it can be seen in a 150mm telescope.
With the toughest catch behind me, I felt exuberant and ready to push north where the sky was more familiar -- and hopefully dark! However, the next obstacle confronting me was the same as the first. Where's Sculptor? Like those in Phoenix, Sculptor's 4th magnitude stars were obscured by high clouds and atmospheric extinction. Once again I would only succeed by first employing the binoculars to "scope things out". The difficulty here was that the dimness of Alpha Sculptor made identification difficult. To attack this problem I started at 2nd magnitude Beta Ceti and, using the finderscope, hopped 1 degree west to a neighboring 5th magnitude star. Then twice this distance further west to line up with Alpha Sculptor some 11 degrees to the south. Dropping those 11 degrees while peering through the finderscope, I noticed 4th magnitude Alpha and an unnamed 6th magnitude neighbor some 2 degrees noth-northwest. All that was required now was to triangulate using the 6th magnitude star as the apex of a tight equilateral triangle and point the main tube in the general locale of globular cluster NGC288. In fact, as I did so, I noted a faint diffusion of light near the expected position and centered the finderscope on it. As it turned out this was the desired 8.1 magnitude cluster.
Initially this globular cluster looked like a sprinkling of light grey sand against a dark gray beach. Given a more northerly location, this relatively dim globular could possibly reveal dozens of 13th magnitude stars. I fully expected this to bear out when I switched over to 120X view. But unfortunately, the low surface luminosity of the cluster (at minus 27 degrees declination) just wouldn't support the additional magnification. So I switched back to 50X and promptly lost the "grains of sand" effect. Due to it's low sky position, NGC288 only showed about 8 minutes of its documented 14 arc-minute diameter. Like most globular's, this one is oblate. In this case, along the north-south axis. NGC 288 is surmounted (to the north) by a rough parallelogram of 9th and 10th magnitude stars approximately 10X25 arc-minutes in size.
To locate NGC253 , I simply swept 1 degree west and 2 degrees north of of NGC288. In doing so I was rewarded with a surprisingly well-defined edge-on galactic disk -- perhaps 20 arc-minutes in width by 8 arc-minutes in height. The plane of the disc is oriented from northeast to the southwest. It is supported along the southeast by two 9th magnitude stars separated by about 7 arc-minutes. (These are oriented along an east-west axis.) Other 9th magnitude stars share the field east and west of the galaxy.
NGC288's galactic "lens" displays a dark band parralleling it to the southeast. It also appears as though the northeast spiral arm is somewhat brighter than that of the northwest. This galaxy should offer a treasure trove of intersting features for larger apertures -- or under even darker viewing conditions in a 150mm.
Compared to NGC253, M74 is uninteresting. It appears as a diffuse circular region about 8 arc-minutes in diameter. Given it's size (and shape) one might suspect it of being a dim globular cluster. But the lack of "grainyness" tends to squelch this notion. I can imagine, however, that Charles Messier probably got pretty excited when he first found this object -- given its basic "comet head" shape and low surface brightness.
The FOV around this galaxy shows subtle variations in texture. Is it possible that we are seeing the core of a top-down galaxy possibly 40 arc-minutes in diameter? If so then this object could be far more spectacular than first suspected...
According to the charts I am using, M31 contains a region of heightened luminosity along the southwest spiral arm consistent with an extensive "star field". Recent attempts to locate this feature on my part have proven abortive. Now under the near "thirteen-oh" telescopic conditions we were experiencing the question of the moment was: "Would it be visible?"
Turning the scope on M31, I moved the bright core of the galaxy just outside the FOV and began examining the spiral arm with "soft-eyes" and averted vision. The first thing I noticed was how much more detail was visible under the current dark sky conditions. Truly, it is possible to get indications of undescribable spiral-swirlings in this handsome neighboring galaxy of ours -- even in a 150mm scope. Setting aside this amazement, I looked for indications of a brighter region in the expected location. What I did see was a rather extensive region of "scintillation" slightly to the southeast of the galactic plane. This region was perhaps 6 arc-minutes wide by 8 arc-minutes in height. I'll need to revisit this region in particular and the entire galaxy in general under similar conditions in the future.
As a result of this evening's session at the Ridge I have now finished 1/24th of my plan for the upcoming year. During this year, I hope, Deos Concedente, to locate and describe all deepsky objects accessible to a 150mm telescope listed in Philip S. Harrington's book "The Deep Sky". (Plus others that interest me based on personal research.) I expect, in so doing, to make more than a few mistakes in identification and description but along the way I can only hope that my skills will sharpen to the point of establishing my credibility as a "seasoned" observer of things astronomical.
End of December 2000 Reports
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