A Star Party, First
Earning My Scope
Eyepieces Anyone?
The Ringed Wonder!
One Superb City of Stars
Gotta Love Those Telescope Reviews
Star Party Shootout
Spectacular Deepsky Night First!
New Toy: Star Diagonal
Continued Star Diagonal Comparison
Enough Star Diagonal Testing Already!
Reports for November, 2000

A Star Party, First

Late afternoon clouds made it doubtful that this star party would be a happening. By sunset, such doubts were banished as the last of Sol's rays chased the few remaining clouds from the slowly darkening sky.

The drive up to the old Bonny Dune airfield was accompanied by my family's best laid plan's for the evening's viewing. The airfield has an excellent southern view so it would be a good evening to explore the rich star fields, clusters, and nebulae of Scorpio and Sagittarius. There was also the prospect of catching Venus before She dipped over the western horizon. The eveing would probably wrap up with some tantalizing views of Saturn and Jupiter (sometime around midnight). Finally, it was hoped that a wide range of instruments and fellow observers would be present to compare views and swap experiences with.

By 7:45 a few observers had gathered. 2 gents brought along binoculars. Our family of four setup a 150mm Maksutov-Cassegrain. The first views of Venus were poor. It was impossible for the 150 to stabilize before Venus dissappeared below the tree line to the west. At this point, it was still duskily light. Vega was just cutting through (as Venus bowed out). The sky darkened enough to find Epsilon Lyrae. At 180 power, the "double-double" was a poor split. The 150 had yet to get its observing legs. (Later that evening all four stars were clearly separated at 120X.)

By 8:15 it was dark enough to begin tackling a few of Scorpio's gems to the southwest. Despite the stability of the sky (perhaps 7 of 10) Antare's proximity to the horizon made a clear view of it's 5th magnitude companion (separation 3 arcseconds) unlikely. An attempt was made -- no surprise. (This would have been a tough split with this scope even with the optic's fully stabilized). The scope was next turned on M4 (near Antares). This is a large bright cluster (magnitude 6.4) but it's low sky position and the residual dusk did not permit of the kind of view that was possible with M22 later in the evening. We turned the 150 on M80 and this smaller cluster suffered from the same limitations...

So now the main event: Sagittarius: M22 was quickly located (seek time for M80 was quite long so it was a bit later and darker). M22 practically exploded with stars at 120X and 180X. All agreed that it was a spectacular sight. Those with binoculars marveled at the difference between "the diffuse starlike spot" seen in their 7*35 and 10*50s to the mass of tiny lights revealed by the 150 at higher powers. With the memory of M22 safely tucked away, we went on to capture views of M28 (a dimmer, smaller but equally compact globular cluster) and M8 (the expansive Lagoon Nebula -- split by a dark lane of interstellar dust and gas.)

It was just about this time that a member of the SCAC turned up. He was able to locate M20 (the Trifid nebula) -- an obscure patch of light in the 150. Later we went on to observe the "Wild Duck Cluster" (M11 in Scutum). Dozens of stars were visible in this cluster at 120X. The arrowhead shape of this loosely globular star group was discernable (with a little imagination).

The sky was getting much darker by this time. The great expanse of the Milky Way was easily followed by the naked eye (from Sagittarius in the south all the way to Casseopiae in the northeast). Views through binculars were quite striking. A large number of open clusters and rich star fields were accessible. Sky transparency reached it's peak about this time (maybe 7 of 10). Conditions were only mildly hampered by the glow from the city of Santa Cruz to the south-southeast.

Some of the binocular-bearing folk decided to lay down on the grass. With the Earth supporting them, they scanned the sky as it drifted slowly overhead. As each new object was found in the 150, attendees would queue up to take a quick look, then retire back into talk or quiet contemplation of the evening's offerings. Eyesight varied widely... It was often necessary to re-focus the scope after each viewer.

M13 in Hercules was easily found. Simple adjustments of eye position would cause hundreds of stars to jump into view. Great arcs of starry points would trace across the field of view at 180X. By contrast, the stars of M22 in Sagittarius were immediately present to the eye with or without aversion of the sight. (Certainly M22 even with its lower sky position is more readily resolved than M13.)

A quick check of Epsilon Lyrae showed that the scope and seeing were at it's best. 120X cleanly split each of the distant primaries. The Ring Nebula (M57 in Lyrae) was easily found. Like most nebula of this type (planetary), it looked brightest with first glance. Subsequently, all that remained was a dull grey smokey ring of low contrast with the sky. Certainly a 250mm scope (or larger) would have enhanced the Ring Nebula's reputation among those in attendance.

Now for the ordeal: The time was around 11pm. Leaving the Ring Nebula, an attempt was made to find the Dumbbell Nebula (M27 in Vulpecula). The first question that arose was: "Who among the ancients would have decided to call this inconspicuous group of 4th and 5th magnitude stars a constellation?" The second question was: "How is it possible for such a relatively bright planetary (magnitude 7.6) to be so elusive?"

After about a half-hour search, the answer to question 2 was clear. (The finder-scope had mis-aligned sometime during the night's use.) Even after re-alignment (and locating M27 in the main telescope), the view was suspiciously disappointing. The answer to this was revealed: It was "the dewing hour". That astronomical rite (the laying on of hands) was performed, the dew was banished from the correction lens and the Dumbbell was revealed in all it's mildly luminous, diffuesly hourglass shaped glory.

Meanwhile to the east, Saturn and Jupiter steadily rose. The 150 was relocated and Saturn to peer above the tree tops. Even at only 20 degrees above the horizon Saturn's equatorial band and the Cassini Division were obviously visible (near the outermost portion of its ring). The dusky inner ring was vaguely apparent, while the planet and its rings stood out starkly against the eastern sky.

Jupiter, even lower to the horizon -- perhaps at 15 degrees -- was equally striking. At 180X it appeared about twice the size of a full moon to the eye. Three of its moons were easily seen (none showed a disk at this magnification). The equatorial belts stood out clearly. Hints of the temperate bands were also possible. At F12 the 150mm Mak Cassegrain shows real promise for planetary use.

By this time everyone had left. We packed the 150 into the trunk and headed home. Despite the low turnout and shortage of alternative viewing equipment, I found this experience satisfying. The expanse of sky seen from the airfield is quite large. There is an excellent southern view. The sky (at 2000 feet above sea level) was very steady. Glow from the city of Santa Cruz was not particularly annoying.

Final thoughts: It would have been excellent to have had a 200/250mm "Go To" scope for events where folks queue up for looks. A huge "light bucket" (300mm or so) would also have been a huge advantage for planetary and emission nebula viewing. The 150 was fine for clusters, planets and double stars but otherwise its long focal ratio / limited light gathering capabilities handicap its deep sky potential. I was impressed with the views through binoculars -- but a large part of this has to do with the presence of the Milky Way's rich field of asterisms and clusters.

to: top of page

Earning My Scope

As a youth I had had a puppy-love affair with all things astronomical. Now some 30 years later, I felt a re-kindling of that same spark. I knew, based on the unformulated experiences of the time, that image-quality and light-collection were the two "top dogs" of observational astronomy. I also knew, as a reasonably mature adult, that "puppy-love" was not going to cut it, and that I'd better get a scope that I could live with. Based on my budget limitations (less than 1.5K), I reasoned that a small refractor (90mm) wouldn't meet my light collection needs, and that a large (cheap) reflector would probably fall flat when it came to image quality.

The Watsonville outlet of the Orion Telescope and Binocular Center lies within easy striking distance of my home in the Santa Cruz Mountains. This particular outlet has an annual "parking lot sale" of "seconds" and general astronomical accessories. I attended the sale and poked arround for a while. Among the scopes I was interested in was the 120mm (4.7") achromatic refractor and the 150mm Maksutov-Cassegrain Argonaut. Both scopes were mounted on the $300 Skyview Deluxe mount. The 4.7" was slightly less expensive than the Argonaut but I new that the additional color correction and 5.5" clear aperture of the Argonaut would better fulfill my expectations -- or so I thought.

As it turned out, the particular Argonaut I purchased was sadly deficient in mechanical alignment. In fact the tube itself was 1/16" of an inch shorter on one side than the other. This made collimation impossible. I ended up damaging the secondary mount while adjusting its position. The folks at Orion were quite wonderful about this and took a return on the OTA for repair. As it turned out, the technician straightforwardly told me that true collimation of this particular scope would be impossible and rounded up another OTA (second) for me to try out. A quick bench test confirmed that the second OTA was much superior to the first. The tech performed a laser alignment and I took it home in exchange.

The coma I had seen in the original OTA was not apparent. In/out focus tests showed some ellipticity. I began a systematically detailed job of re-collimating the optics. This involved the use of mechanical shims in the focuser and the star diagonal. The process of aligning the scope to perfection took about a month. To be honest, I actually enjoyed making the adjustments. (It's amazing how much you can get out of dealing with such problems intelligently.)

Last week I took the completely aligned scope to a star party hosted by the Santa Cruz Astronomy club. A wide variety of scopes were available for views. As it turned out, the two best scopes were neighbors to one another. The gent next to me had a fine 10" Dob. It gave exquisite views of deep fuzzies and extended nebularities. Equipped with an OIII filter, it's view of the Veil Nebula in Cygnus was exquisite with delicate detail. I was also blown away by its views of M22 and other deep-sky wonders. After seeing these things could I possibly be happy with the "deep-sky" performance of the 6" apertured Argonaut?

In the Argonaut, M22 looked like a dull hazy patch. Visitors to my scope could barely find it in the FOV. Something clearly was wrong...

As it turned out, the particular eyepiece installed in the Argonaut was a 25mm Plossl -- complete with moon filter attachement! Removing the filter quickly restored my faith in the excellence of this scope. To be honest, the 250mm Dob gave brighter, higher contrast views of "M" class objects (you know M13, M57 etc.) but when it came to splitting double-stars and views of the planets, the 150 was unsurpassed. The combination of long focal ratio and excellent optical surfaces, properly aligned and collimated could not be bested.

Comments To Potential Telescope Buyers:

So, if you are looking for a highly portable scope with razor-sharp imaging capability. You can spend 3K for a 4.5" apochromatic refractor, or half that for a larger Maksutov-Cassegrain. (Don't let them sell you an SCT -- they are simply not in the same class.)

No matter how good the scope you end up getting, there are a few factors completely out of your control - the weather, sky conditions, and the elevation of a particular object above the horizon. So, if for some reason you are not happy with the views you are getting through your new scope, take the time to ensure that it is completely collimated - then pray that the sky clears, the air steadies, and that the power goes out in local community for a couple hours at a time when Sagittarius is on the celestial meridian, or Saturn is high on the ecliptic...

And oh yes, take my wife's excellent advice, do what it takes to buy your last scope first. If you are into deep sky stuff get the largest Dob of excellent optics you can safely break down and transport personally. If you are into lunar & planetary views get a fully apochromatic 100+ mm refractor. If you want the best of both worlds, purchase a Maksutov - Cassegrain or (Newt) of at least 150mm aperture. Then, from that date on, spend your loose change improving your eyepiece and filter collection. Add a decent clock drive, maybe electronic setting circles then find some kind of engaging astronomical project to set off on. Finally, be sure to attend lots of Star Parties. Share the Experience!

to: top of page

Eyepieces Anyone?

The 35mm Orion Ultrascopic is my "go to" eyepiece for extended M-class objects (Messiers) and star fields. Pick one of these babies up until you can drop the 500+ dollars on a Panoptic or Nagler SWF. You may find you never need make the investment (or decide to add to your filter collection instead...)

Stars are pinpoints (but in 1 degree fields, most good oculars provide "stellar" performance). Some coma is seen at the extreme edges. Bright contrasty images are apparent, but large halos of light are seen around the brightest stars. Color correction is fine. Eye relief is almost too good. (Requiring that you take a stable body position well away from the top element.)

Incidently, I also have the 25, 15 and 10mm Ultrascopics as well. At 70X, the 25mm shows both Epsilon Lyrae components as elongated during good seeing. The 120X 15mm easily splits the pair in my 150mm Argonaut on decent seeing nights. Eye relief on the 10mm is rather short. (The top element tends to get an "eyelashing" and requires frequent cleaning.) I also have the 25mm and 9mm Plossls. These perform well too - although they seem slightly less contrasty, have a rounder field and more internal reflection. (The Plossls came with the scope, and after evaluating them head to head with the Ultrascopics I might have done better to just use the Plossls at 25 and 10mm until I could afford 2" eyepieces.)

to: top of page

The Ringed Wonder!

Woke up early in the am. With sleep eluding me, decided to pay respects to the (very) late night/early morning sky. Knew that Jupiter & Saturn would be near the meridian. The sky was clear with a near full moon. My scope had only recently been fully collimated, so, all things considered, conditions were ideal for planetary observation.

Saturn's ring presentation was glorious (although not at fullest extremity). Cassini division clearly delineated (as though etched into the transition between Ring A and Ring B). Ring A itself was obviously darker and somewhat "striated" in texture (Encke division suggested but not explicit.) Ring C was discernable east and west of the planetary globe. (The black of the void blending into Ring C's duskyness.) The inner dusky ring also caused a visible darkening below the bright equatorial band of the planet. A dullish ruddy-yellow equatorial belt was easily seen above the brighter equatorial band. The northern terminator of the planet displayed a dark line between the limb and ring behind the planet. (I did not expect to see anything like this and was simply amazed at the sight.) I did not count the moons but several were visible (unlike Jupiter's moons none showed the hint of a disk.)

To date, the above view of Saturn is the best I have ever seen through my (or any) telescope. it would suprise me to ever see it any clearer (although I would have loved to have a 2x barlow available to look for Encke's division and possibly additional surface textures.) Generally I am very pleased with the quality of image possible with a good 6" inch telescope. Finally, it's unfortunate that I didn't fully document my observations at the time but I offer this up to those visiting your site to provide a sense of what can be seen on really good seeing nights when the planet is well above the horizon.

NOTE: Most views of Saturn -- besides the above have, in fact, been very dissapointing... Usually, the planet looks like it's "boiling in oil". Snap to focus is impossible. The Cassini division is normally only hinted at. However, as you continue reading this series you will note that I eventually eqipped myself with an Orion Ultrascopic barlow lens. In addition, there was an excellent string of stable sky viewing experiences that put the lie to the idea that the above seeing was "once in a lifetime".

to: top of page

One Superb City of Stars

Last evening there was a short break between two storm fronts passing though the SF Bay Area. I knew that if I wanted to bid adieu to the wonders of the galactic core (Sagittarius) I would need to get the scope out somewhere reasonably dark with some kind of view to the southwest. So I packed the argonaut up, placed it in the trunk and drove the short distance to Boulder Creek's best kept night sky viewing secret. (SHHH, don't tell, even if I have.)

I had the scope assembled just as Vega was visible in the early evening sky (on the meridian above me.) Out of focus tests showed that tube currents were present between the meniscus and primary, but what the heh, I did a quick check of Epsilon Lyrae, just for giggles. (Surprisingly it split cleanly at 120X with no contact between spurious disks -- a first for this scope.)

Once things darkened up reasonably, and with Sagittarius sinking rapidly to the southwest, I swung Argo around and easily picked up M22 (about 5 degrees above the treeline). For the next 30 minutes, I silently gazed in wonder at it's glorious swarm of 11th + magnitude stars. (This as it glided effortlessly into the treetops.) At 120X I could see about 200 discrete stars all the way across it's otherwise blurry, slightly distorted disk. (The core itself was not resolvable -- only the brighter stellar components in front of it, as well as those in the lesser populated outer 20% on either side.

Switching over to the 50X 35mm Ultrascopic, it was obvious that considerably fewer of the globular's stellar components were accessible (perhaps 50 or so -- and all in the outer 10-15% of its domain). However, as M22 drifted into the treeline, I was amazed by a sight that we don't often get when peering into the deep sky, namely enough light to make out the shape of the tree tops while at the same time being just dark enough to clearly discern detail in a deep sky object. It was this that struck with me with a keen feeling of especial connectedness between the Earth of everyday experience, and the immensity of a distant heavenly "body" composed of over a half-million suns as it moved effortlessly across my field of view. Is it possibly this connection that drives amateur's such as ourselves, to make solitary trips to distant (or otherwise) locals in search of the occasional exquisite view of the cosmos?

to: top of page

Gotta Love Those Telescope Reviews

Like all performance scopes, the MK-67 is heavily impacted by seeing conditions -- especially on planetary objects. However, under stable skies (not necessarily clear), Saturn displays a laundry list of features (Cassini division, inner dusky ring against the planet body, shadow of body on B-ring, unresolved striations in A-ring -- hints of the Encke division --, north equatorial belt, a broad equatorial band at planet waist, up to 5 satellites.) Views of Saturn are simply transfixing (though, in my opinion, no real "work" can be done with Saturn using such a modestly sized scope.) But you will find yourself returning to it time and time again and also revisiting your perplexity of how it can look so good or so bad depending on the sky...

Jupiter's satellites are obviously not stars. (Although if I had more than a 200x ep, all four Galilean's would probably display a disk.) Six belts are visible on the surface (the equatorial belt splits into a central and southern component) plus the two NEB's and 2 SEB's. At 200x, I have not seen detail within the EB, but irregularities in its edge are often apparent. Finally the "Great (not so Red) Spot" is visible when present. I would say that the 34% central obstruction of the MK-67 reduces image contrast on Jupiter. For this reason, surface details may not be obvious to less-experienced observers. In terms of serious "work", MK-67 users can probably make useful contributions in the area of satellite- and the occasional NEB disturbance- transit timing but little more than this...

For deep-sky use (more important to me personally than viewing planetary detail), the MK-67's long-focus gives up a little to shorter-focus 8" Newtonians (in terms of light grasp and image brightness). However, the MK-67 provides superb definition -- when sufficient light is present. (M42 is a religious experience, brighter globular clusters resolve in ways comparable to that reported about 8" Newts rather than 6" models). For lesser surface brightness "deep-fuzzies" (such as the Ring Nebula) a lot depends on the observer's experience in "seeing" faint detail or variations in image intensity. In viewing the 52 Cygni region, for instance with both the MK-67 and a decent 10" Dobsonian Newt (using an OIII filter), the 10" Dob will show you filamented nebulae which just happen to have stars embedded in them. The MK-67 will show you star arcs that just happen to be connected by faint nebulosity. Surprise! Aperture wins!

NOTE: I would say that the bottom line of deep sky and planetary observation with this scope is that you have to learn to really "sense" deep sky subtleties more readily apparent in 8" reflectors and scrutinize for planetary detail distinctly present in 5" refractors.

Color-correction in this scope is outstanding. Star images are better than SCT's of any size. Star-tests show textbook perfection inside focus while outside focus tends to be slightly "mushy" -- but still quite good. According to the literature, this suggests that the optical configuration is slighly under-corrected.. Compared to an APO refractor however, the MK-67's central obstruction exaggerates the size of bright-star spurious disks (at similar magnifications). (Vega's 180X disk, for instance, is probably 4 arc-seconds in diameter, however it's 10.5 magnitude companion is not over-powered by light-scattering.)

During much less than ideal sky conditions (Milky Way not quite visible), I have seen stars photoelectrically measured at magnitude 12.8. I suspect that under ideal conditions, the threshold limiting magnitude is closer to 14. (This is a little better than most 6" scopes, but if you keep in mind the excellence of the optics, this should not be surprising.)

In general, I would knock the OTA down a notch for a variety of reasons: First, the contrast of fine planetary detail is hindered by the rather large size of the central obstruction. (This same phenomenon also negatively impacts double-star resolution where a bright primary is present -- Antares for instance). Second, the amount of back-focus is limited (although you can optimize to your eyepieces if you are willing to play around with the secondary mirror position.) Third, the scope takes a while to stabilize under rapid cool-down and is subject to frequent dewing of the meniscus. (Heat must be applied several times over a typical four hour observing session. -- A dew cap really helps here.) Fourth, the finderscope has poor edge correction, obscure cross-hairs (OK for planets -- but not deep-sky), and is mounted far too close to the optical tube and focuser. (Note to manufacturer: I understand that it is so close to make it easily stored in its case but...) Finally, the observing position is poor for objects directly overhead when using standard leg-length tripods on GEMs. (I have to sit on an observing stool to offset this problem -- or else exploit the ample opportunities to work on my "horse-stance".

Concerning quality assurance of the Intes scope: In general, it appears that Intes consistently sources high-quality optics, however, the mechanics of the scope can occasionally be off significantly. (I personally found it necessary to "shim" the focuser body to the optical tube in order to ensure that the center of the on-axis light cone is properly positioned in the ep. (I also had to shim the inexpensive 1.25" mirror star diagonal I use for the same reason.) Because these scopes are becoming ever more popular, I would assume the necessity for such "ad hoc" alignment aids will only increase -- so be forwarned.

Despite the above nit-picking, I would say that MK-67 performance exceeds that of a 4" APO on planetary detail and is comparable to the average 8" Newtonian on deep sky. Not too shabby for a scope that is easily set up. and can be handled as "carry on" luggage during air travel. The real question before the deep-sky amateur is this: "For $1K, why would I buy a 6" when I can pick up a decent 10" Dobsonian?" The answer is simple: Get the 10" Dob -- unless you also have a penchant for outstanding planetary views, frequently travel with your scope, want an equatorially mounted scope that can be stored and moved about locally as a single unit, or have a penchant for terrestrial observation that parallels your astronomical interests.

to: top of page

Star Party Shootout

This party was located at the Bonny Dune observing site (altitude 2000 feet) near Santa Cruz California. Four scopes were available for viewing: a 1960's era hand-made F8 6" reflector, a 150mm Maksutov-Cassegrain, a 200 and a 250mm Meade SCT.

The home-made 6 inch arrived late and -- juxtaposed against the more modern Maksutov-Cassegrain and SCTs, -- reminded me just how far amateur equipment has evolved since the 1960's (when I had my first, youthful, cycle of interest in amateur astronomy...)

So here sat three contemporary catadioptic instances of the genus "amateur astronomical telescope". Why not do some comparison veiwing?

We started with Venus. Yuch, low sky position and tube currents killed us all.

Next...

Epsilon Lyrae: Clean split in the 150 at 120X. Dirty split in the 200mm at 200X. Didn't get a view through the 250...

Iota Cassiopiae: Clean split in the 150mm at 120X. Didn't get a view through the others. (Adding this for future reference.)

M57: Same basic views in all three with the 10 inch giving the brightest view. The 150mm barely catching a 13th magnitude field star. The 200mm a little surer on the field star. The 250mm revealed some 14th magnitude field stars as well.

M56: 150mm showing about a dozen stars under more or less direct observation. 200mm did slightly better. The 250mm showed about a hundred without a hitch. All at roughly 200X.

Western Veil Nebula: The 150 and 200 showed a continous stream of quite perceptible luminosity flowing down from above 52 Cygni and taking a left turn across the field of view. (All scopes shared the one available OIII filter.) No chance to view the Western Veil in the 250.

Eastern Veil Nebula: Got a look at the Eastern Veil through the 250mm. But it needs a much lower power ep to make any kind of comparison with the view I'd seen through a 10 inch F4.5 Couter Dobsonian at a previous star party. (I suspect that the Coulter Dob would probably give the better view -- the Dob's optics were simply outstanding.) The views seen through the 150 and 200 were comparable to one another -- but I was not able to spend much time on either before high clouds reduced the contrast past the toleration point and we switched over to pay our regards (for the rest of the evening) to the planets.

Saturn: Cassini Division, South Equatorial Belt, South Polar Darkening, Dusky Ring C -- before the planet and shading toward the planet --, Southern Polar Cap Limb Ring Delineation, Encke Gap (at the extreme Ring ansae). All scopes. 250mm giving the brightest image at 500X, 150mm giving the sharpest image at 360X.

Jupiter: NEB & SEB (with parallel belt splitting) edge irregularities, and festoons, NTB. All scopes. Edge to 250mm for contrast and image brightness. 150 had the sharpest image but lost out on surface feature contrast.

Consensus of partcipants: The 150mm Maksutov-Cassegrain had the best optics. The 250mm Meade had the brightest images. The 200mm needed to have the meniscus cleaned. All three scopes performed well on the planets at high power -- under the exceptional conditions experienced. The 250 owner was blown away by the planet views through the 150. The 150 owner was impressed by the image quality of the planets displayed by both SCTs. (Both SCT owners felt they had received "best of breed" SCTs in this regard.) One attendee's comment: "Based on what I saw through your 150mm, you'd need to get at least a 12 or 14 inch telescope before you'd want to replace it -- especially on the planets."

In sum, a 150mm telescope possessing well-maintained, high quality optics can get respect from deep-sky and planet lovers alike. So do what it takes to bring your 150's up to spec: (Alignment, aluminization, re-grinding -- whatever it takes.) If you've got a quality 6 inch, don't even think about getting anything else until you have to consider building a small observatory to house it in!

to: top of page

Spectacular Deepsky Night First!

Due to an engagement earlier in the evening, we were unable to get to this event until later (10:00pm). It was also my first attempt to locate the observing site after dark. After seriously overshooting the turn, we managed to backtrack to the entrance. Headlights off, short stop for dark adaptation, roll into the parking area...

There was one car in the lot. Earlier in the evening, the sky didn't look particularly promising. So I wasn't surprised at the turnout. (That attendee -- Leon -- had himself just turned up and was in the final stages of setting up his 10" dob.)

The sky was very dark (with the exception of considerable glow from Santa Cruz to the south-southeast). Jupiter and Saturn were approaching the zenith overhead. Jupiter, stationed near Aldebaron, had a particularly awe-inspiring effect on the sky. His Majesty's brilliance seemed to "illuminate" Aldebaron and the Hyades star cluster like a radiant gem amongst a myriad lesser jewels...

By this time, Leon had turned his dob on Jupiter and Saturn. Meanwhile, my son Eric and I assembled the equatorial mount and secured the OTA. (The only real hassle with setup is fitting the eyepiece tray -- which also holds the tripod together.) Between steps I looked at the dob's 110X views of Saturn. Due to the low magnification, little detail was discernable other than Cassini's division and the planets equatorial band. Several satellites were in Saturn's attendence.

Eric and I configured the scope (with barlow in 3x configuration) and inserted the 15mm ep (360X). The view was satisfactory -- but not as sharp as we have seen it. The view of Jupiter was better, and unusually bright. (The medium blue filter was a real help here.) Leon, Eric, Vanessa (a family friend), and I took turns at the ep. The two equatorial belts were easily split. Irregularities in the north equatorial belt edge were clearly depicted. Festoons within the belt were present but not distinguishable. The hollow of the red spot was also apparent (subtly, certainly not definitively, positioned on the globes central meridian). A quick check at 540X showed what I suspected: Stability was only fair to good, but certainly not excellent. This was a night for views at 210X and 360X.

Orion was now well clear of the horizon. I reconfigured the scope to remove the barlow lens system and switched over to the 35mm ep. At 50X, "The Great Nebula" (M42) was simply spectacular. The jet black of an intervening dark nebula struck a stark contrast to the soft white luminousity of the reflecting nebula behind it. The nebula in its entirety spread out like a beautiful flower encompassing the various stars (the Trapezium et al) in its midst. Truly a magnificent sight. M42 is perhaps the only example of a reflecting nebula that can be truly "studied" in great detail with a modest telescope.

Just for the experience, I decided to take a quick look at the "brightest star in the night sky" - Sirius. While turning the finderscope on it, I noticed a rather compact open cluster about 4 degrees to the south. Like M42, the cluster (M41) did not quite fill the 1 degree FOV. Several hundred stars were easily resolved. These ranged from about the 7th to below the 13th magnitude. Each star a tiny sharply delineated ember glowing amongst the jet-black coals in the deep of space.

After seeing Sirius completely dominate the ep, I consulted my charts for "first light" finds in the region. One object (M78) caught my eye. Orienting the scope roughly 4 degrees northeast of Epsilon Orionus, I was surprised how easily this pale white nebulosity was picked up in the eyepiece. This "smudge" was seen in curious relation to a small group of neighboring stars. The total effect is that of an osprey, wings spread in a glide, talons touching down in the ocean of space. (The asterism and associated nebulosity all fit in the same one degree FOV.) I will most definitely revisit this sight again and again as the winter constellations begin to dominate my observing sessions.)

Next "first light" was M79, an 8th magnitude compact globular cluster. The plan here was to determine whether any of it's component stars could be revolved in a 150mm scope. As it turned out, results were inconclusive. The globular's low position (within the Santa Cruz sky glow) did not give the kind of deep black background needed to show 13th magnitude stars. At best, using averted vision, the globular gave a "mottled" appearance with occasional glimpses of a handful of its brighter components.

Another first light was the M1 "Crab Nebula" (about 1 degree northwest of Zeta Tauri). Surprisingly, the Crab Nebula was rather easily picked out against the darker sky near the zenith. Even at 50X it was fairly conspicuously sized. It looked like a subtle gray cottonball gently squeezed to elongation. It even gave a small sense that, unlikely planetary nebulae, it had no well-defined transition to the blackness of space surrounding it.

By this time, the occasional high, thin clouds seen throughout the evening were beginning to pile up. We took what opportunity was left to search for NGC 1535 (located about 4 degrees east of Delta Eridani). Despite continual sweeps of the sky in the general locale, this rather large 9th magnitude planetary could not be found by myself on the 150 MCT or by Leon with his 250mm Dob-Newt. Something to look forward to on another evening...

Throughout the evening, Leon and I exchanged views through our respective scopes. As you might suspect, his 250mm scope showed everything deep sky as somewhat brighter and with greater contrast. (But not so much brighter or contrasty that it was a "quantum-leap" in improvement.) Once again, as at the previous Saturday's star party, I concluded that a 150mm scope is a fine all-around instrument capable of supporting a lifetime's worth of explorating the wonders of the planets and the deep-sky alike.

to: top of page

New Toy: Star Diagonal

The mirrored star diagonal originally received with my scope has always been suspect. Early on I had to "shim" the mirror into position within the diagonal holder to get a reasonable on-axis light bounce from the secondary into the eyepiece. In addition, the diagonal appears to diminish the brightness of common objects viewed through it (statically). A certain amount of edge distortion is also present. (This shows up when viewing star fields and making checks viewing grid lines -- such as venetian blinds). The diagonal may also contribute to "spurious glow" around stars (8th magnitude and brighter). And can contribute to contrast issues associated with planetary detail (especially Jupiter). All in all, it made sense that some of these problems could be overcome by replacing this item with something of superior quality.

NOTE: Star diagonals are commonly used on MCTs (like mine), SCTs and refractors. Even Newtonians, however, can have analogous problems with their secondary mirrors.

Two weeks ago I put in an order with Orion Binocular and Telescope for a replacement unit. As it turned out, what I wanted was not available on site so they back-ordered the part (PN 8778 a 50 dollar 1.25" unit manufactured by the Vixen Telescope Company of Japan). Notice came by phone earlier this week that the part had arrived. I was also told that an optical technician had inspected the diagonal and confirmed its quality.

Friday afternoon I drove down to Watsonville to pick up the new diagonal. While on the premises, I made a quick visual inspection. The aluminized mirror surface looked flawless. I peered through it at some venetian blinds (an impromptu "ronchi" test). The lines looked straight (except, to my eye, near the periphery of the mirror). Images reflecting off the mirror didn't appear appreciably "darker" than those seen natively. The unit was well crafted and much heavier than the older diagonal. With the exception of a slight distortion seen at parallel lines near the edge of the mirror, I was pleased.

On getting home, I mounted and assembled the scope. (Due to mechanical difficiencies with the old diagonal, I had to re-collimate the secondary.) With eveything in place, and the light cone falling squarely into the eyepiece, I set eveything aside -- and hoped the weather would prove cooperative later in the evening.

I had no illusions about being able to put the new diagonal through a full observation series. Currently the moon dominates the night sky, and lately high, thin clouds have been regular visitors to -- or should I say interruptors of -- my nights out. However, around 9:00pm I returned from an evening out and set up the scope for planet views.

Jupiter:

In observing Jupiter, first thing I noticed was that belt to body contrast seemed better. (This despite the fact that high thin clouds were present in the atmosphere above me.) Jupiter's NTB was clearly discernable and showed variations in texture along its length (something I had never noticed before). In fact, the north polar region hinted at texture -- rather than the normal uniform darkening to the polar limb. The twinning ("split") of the NEB was quite obvious. For the first time, I noticed some hint of a very narrow, low contrast "equatorial belt" running straight across the waist of the planet.

NOTE: For completeness, I should mention that the SEB appeared a single unit this evening -- there was no visible split between the broader, higher-contrast southern and thinner, lower-contrast equatorial component. (There did appear to be a slight "brightening" of the region between the two components however.) The STB was not visible, and unlike the north polar region, there was no hint of texture at the opposite pole.

In viewing the Galilean's, I was pleased to see that all four moons showed "clean" disks at 360 and 540X. (Yes, stability was that good.) In addition, the amount of glow surrounding each disk was appreciably less than seen in the past. The glow itself was also more concentric and "airy" in nature. (A comet-like glow associated with Jupiter's moons was one of the things that recently alerted me to ongoing failings with the old diagonal.) It was also clear that each Galilean shows a different size disk, of varying surface brightness and hue. (I definitely need to spend more time exploring these characteristics in later viewing sessions.)

I re-installed the original star diagonal (briefly) to compare views. Other than differences in the Galileans, I wasn't able to see enough change to make any bold claims that the new diagonal was a "huge" improvement over the old one except...

... except that later, after viewing Saturn and just before putting away the scope, I tried both diagonals with the sky clouding over. With Jupiter barely perceptible to the unaided eye through the clouds, I could see considerably more detail on it using the new diagonal.

Jupiter viewing continued for about an hour at various magnifications -- 210, 360 and 540X (using 25/15 & 10mm ultrascopics through a 3X ultrascopic barlow). I also pulled out two filters (blue and green). (As usual, the filters revealed nothing I couldn't see directly.) Views at 360 and 540X were required to see textures associated with the NTB & NPR. Through all this, I was pleased with the overall contrast of detail. (As mentioned, I've had problems with image contrast in the past.)

In reading the above, you'll note that I saw some new (for me) "features" of Jupiter's atmosphere and moons. In viewing Saturn, I also noticed some new stuff -- although I spent less time viewing "The Ringed Wonder" than Jupiter.

In past Saturn tours, I had never really taken the time to see if I could trace Cassini all the way around the ring system. Tonight, I decided to see if this was possible. As it turned out, I was only able to do so (using direct vision) at 540X. (It could be done at 360X but required averted vision.) While inspecting the ring, I noticed its shadow falling on the planet's limb. (Previous sessions showed the shadow of the planet on the ring behind the globe, and the shading of the planetary equator by the dusky ring, but I'd never seen the shadow of the ring on the globe itself.)

Even through the high thin clouds I could make out 4 of Saturn's moons. The dimmest occasionally dissappeared as the clouds thickened. The largest/brightest (Titan) hinted at a disk -- but only at 540X.

NOTE: Again for completeness: Saturn's equatorial belt was visible this evening. (Although it seemed to shade into the polar region.) Meanwhile, detail in Ring A (the Encke Gap?) was more plainly visible than previously (and visible at both ring ansae). The ring system is beginning to recede from its peak presentation angle (of about a month ago). I did not see the shadow of the planet on the posterior ring surface. Ring C was easily picked out blending into interstitial space (in the direction of Saturn's globe). Anterior Ring C clearly darkened the body of the planet behind it. The planet showed definite darkening at limb edges. Perhap's my only disappointment in viewing Saturn is that I am as yet unable to make out any detail or texture on the body of the planet or its one visible belt.

In Sum:

Without the use of high grade optical equipment, it's hard to objectively tell how much of a performance boost is had by upgrading any particular component in the optical path. So far, the biggest improvement I've seen in my scope's performance has come about through proper collimation. (Getting the on-axis light cone to converge into the very center of the eyepiece is critical.) Based on preliminary observations done this evening, I believe that the Vixen star diagonal was a solid investment. Improvement in the definition of the Galileans (along with a reduction in spurious image brightness, and size) is perhaps the most definitive fact I can point to. Keep in mind, however, that such improvements may be the result of better mechanical qualities (impacting collimation) than that of the new diagonal's mirror. Finally, I would note that several new features of Jupiter's moons, its atmosphere, Saturn's moon Titan, and Saturn's ring system were noted this evening. It is possible that the new star diagonal (whether through it's mirror surface and/or mechanical properties) contributed to revealing these new features.

More testing is needed. As I do so I hope to answer the following questions: Will my extra-focal star test clean up the "mushiness" I have seen to date? Will I finally see the Crescent Nebula? (And not just a bunch of field star haze.) Will I be able to regularly make out the 13th magnitude field star next to M57 during less than ideal viewing conditions? Will the compact 6.5 magnitude globular cluster M15 prove susceptible to resolution without extreme averted vision? Will I ever again feel the need to get new stuff for my 150mm Maksutov Cassegrain Telescope?

Stay tuned!

to: top of page

Continued Star Diagonal Comparison

Did some terrestrial testing using the new star diagonal this afternoon. To do so, I viewed a distant hillside from my backyard. I found little in the way of obvious differences between the two diagonals in terms of image quality. However, some subtle differences presented themselves:

1. The new diagonal has a slightly "flatter field".

I tested this by viewing details visible in a canopy of trees. During the test I used the 35mm Ultrascopic ep (which shows a 1 degree FOV.)

2. The new diagonal supports slightly better "eye accommodation".

Using the same terrain, I found that the eye tended to "find focus" on subtle details more quickly and sustain that focus over a longer period of time using the new diagonal.

Of the two, the flatter field is slightly more obvious. The "sustained accommodation test" came out of something I noticed when viewing star fields with the old diagonal. Basically there was a tendency for field stars to regularly "twin up" or de-focus once focus is set up. I'll most definitely check for this phenomenon with the new diagonal next chance I get...

to: top of page

Enough Star Diagonal Testing Already!

While at work this afternoon I found myself frequently checking the sky. Noticed lots of fluffy whites and open blues so I engaged planning gears for taking the scope up to BC Elementary School this evening.

Arrived around dusk (5:30) set up in time to do some star testing on Vega. Noticed a little tube current -- but not bad. (Tube current looks like a "teardrop" shape that switches position in the ep when you go inside and outside focus.) As things settled down, I began the star test in earnest. I found that there was a difference between the outside shape of the intra- & extra-focal diffraction patterns. Outside of focus the western edge of the interference pattern seems to sag (or deflate) while inside focus it is perfectly circular. To me this suggests that the focuser is not moving the ep in and out properly. (Basically it "droops".) I may have to re-shim the focuser next opportunity to offset this. While re-shimming, I'll also have to re-collimate the secondary (because the sag does not appear "intra-focally").

While the general shape of the outermost diffraction ring can be used to check optical alignment, the inner diffraction rings tell you a lot about the quality of your optics. Past testing showed that the Intes optics were supurb inside focus but slightly mushy out of focus. (This is interpreted as "under-correction".) The new star diagonal seems to have helped here. With the exception of the extra-focal sag, the interference pattern looked really clean both inside and outside focus.

Now I just have to clean up the mechanics...

Another concern I had (which helped prompt the purchase of the new star diagonal) was field curvature while using the 35mm (50X / 1 degree FOV) Orion Ultrascopic ep. While viewing star fields in Cygnus (and later looking at the Pleiades), I pretty much determined that the problem is NOT caused by the old diagonal. (Although the new diagonal may very well help here.) Basically, the problem lies either in the eyepiece or in the optics as a whole. So I guess, sooner or later I'm just going to have to spring for a "super wide field" ep. (Sigh...)

NOTE: This particular eyepiece seems to have a general problem with focus as well. My eye just can't seem to come to rest (fully accommodate). Stars keep twisting and turning or even splitting in two all over the field -- especially when I shift my viewing angle -- but even while the eye is at rest. The problem doesn't seem to surface with the 25mm -- but I need to pay more attention next time I use it.

One of my bigger issues has been the amount of "quasi-nebular glow" around field stars. This is really annoying -- especially when looking for faint nebulosity (such as that associated with NGC 6888 -- the Crescent Nebula in Cygnus). It's bad enough that the imagination is already busy at work conjuring up nebulosity wherever you expect to find it. But the hazy glow IS real.

This evening, at least for a while, I only had to deal with imagined glow. But then the usual suspects -- high thin clouds, intermediate haze, and low flying fog -- started converging and I started seeing nebulosity everywhere. (The meniscus was clear of dew, but I suspect that eyepieces -- and possibly the diagonal -- are collecting the stuff.) So historically, the real culprit has probably been 85% "California Cold & Damp" and 15% star diagonal / other causes. For you see, just after astronomical dusk (about 6:30) I was getting a fairly glow free view of the "Cresent Five" (part of the "M" Asterism associated with NGC6888). But by 7:30 (when the temperature began to drop and sky began to fall) I was finding nebulosity shot through the Pleiades (possible, but not when the unaided visual limiting magnitude is about 4.0).

A couple other things, while viewing the "Crescent 5" at 50X, I may have actually caught the nebulosity I've been looking for (just my 'magination, running away with me). A switch to 180X did not show much (except perhaps traces around a few stars). While viewing at 180X, I noticed I was getting sharper stellar pinpoints than in the past.

Final thoughts:

OK I admit it. I've done everything I can (within a limited budget) to get the most out of my 150mm, F12 Maksutov-Cassegrain. The goal is to have a portable, dual-use telescope that gives both excellent planetary and decent deep sky performance. During my quest, I've upgraded:

• The Optical Tube Assembly. (The original was hopelessly whacked out mechanically and could not be collimated.)
• Eyepieces: Originally received a pair of Plossls (25 and 9mm) now upgraded and augmented by a series of Ultrascopics (35, 25, 15 and 10mm).
• Star Diagonal: (Upgraded from a generic $15 to a $50 Vixen unit).

Of all these upgrades, I've got the most bang for the buck by replacing the OTA with one that could actually be collimated. Of the other two upgrades, I would say that I needed the 35 and 15mm eps -- but the 25 and 10mm are redundant. (Offer me $120 for the pair and they are yours???). Despite the subtle observational differences between the two star diagonals, the new one is a keeper.

Expanding on this thinking, I have also added a few accessories over the past few months as well:

• An OIII emissive nebula filter.
• A "starter filter pack" for planetary viewing.
• An Orion Ultrascopic Barlow Lens.
• An Orion Right Ascension clock drive.

The jury is out on the filter pack, but the other three items are essential for anyone who wants to view both planets and deep sky. The OIII filter is a real boon when searching for and viewing low surface brightness nebulosity (such as the Veil Nebula in Cygnus). The Barlow allows the excellent Maksutov-Cassegrain optics to really stretch its legs during stable-sky planetary viewing. The clock drive supports the barlow. (Or whenever magnification exceeds 210X.)

Among the things I will probably never get is a "GoTo" mount, but a super wide field 40mm Panoptic or Nagler sure is a deepsky temptation. While a high quality 3 element 15mm Kellner would make a fine high-contrast planetary tool. Of course, I've also heard that a good skyglow filter can really help out in the backyard and during general planetary use. Why maybe ...

to: top of page

End of Early Lights Reports

to: top of page

to Reports for November, 2000

to: Yearlong Reports Archive Page

to: Astro.Geekjoy Home Page

Email: Astro.Geekjoy