Midnight At the Sky Oasis

by Jeff Barbour


Yesterday's sky did not show a great deal of promise for the evening that was to follow. But there was the possibility... Sure, the Sun popped out now and again, but billowy cumulous clouds pretty much ruled the ocean above. And there was something that said "fair weather ahead". Most of the clouds were self-contained and isolated. They didn't sprawl across the sky in veil-like layers. These clouds had clearly defined frontiers and tended to pile upward away from the earth below - like low rolling sky-hills. Yes, there was a possibility of night sky, but no guarantee...

By sunset, the promise had turned into the reality. It was almost like the luminosity of the setting sun pushed the clouds away to the east. Meanwhile, despite a rather trim figure, Selene lay well overhead. This caused me to marvel at how such a thin sliver Moon could lie so very distant from the solar luminary.

But that view was pretty much restricted to the unaided eye. Family plans were in the works. Son Christopher had completed another solar cycle and a pizza celebration was in the offing.

By the time we returned from our jaunt into town, dusk was well progressed.

After family time inside, I dragged 150mm MCT Argo out of the study and turned first to Jupe and then the Moon. The night air was quite chill, and Argo felt warmish to the touch. I knew that between the semi-blustery winds of the day - now significantly diminished - and the tube currents of the night I could not expect a particularly fine view of either body.

There was no surprise in seeing a blurry-limbed Jupiter. Only the two main belts were prominent. Nor a Luna whose features "walked in waves" across the surface. Still, Mare Crisium - as always - held an engaging charm while a few craters - notably Posidonius - showed intricate interior sculpting. had this been my first look at Jupiter through a new scope I would have been very dissapointed in the optics. But me and Argo been around a while now. I know poor seeing from poor optics. And Argo's optics are not poor to say the least. So that left the seeing...

I didn't observe the Moon for long. Soon an entirely different kind of cloud rolled in - and, though the sky directly overhead was transparent, it began to sprinkle! Not wanting to put Argo to service as a "rain guage", I hastily retreated, scope in tow back to the study...

Later that evening - say 11:00PDST - wife Sharon and I leashed up our canine-bud (Ajax) for a walk. Previously, I'd fallen asleep on the couch while reading Burnham's comments on the fabulous Beta Lyrae Oscillatory Blue Giant spectroscopic pair. (No knock on Burnham, I was simply tired.) Once outside and refreshed by the chill winds, caught site of a descending Leo against a not too shabby sky. It was then that I knew upon our return, I was going to take up a bit of deepskying - especially with the nearly extinguished western Moon.

So after doggy-walky, out comes Argo for scopy-walky. My goal? To resume a tour of galaxies located south and east of the Big Dipper's bowl. But before that the plan was to take up the quest of disparate double star nemesis Upsilon UMA.

Knowing that widish and faint disparate companions - such as 10 arcsec separate / 11.5 magnitude Upsilon-2 - are more susceptible to low magnification, dropped in the 70x 25mm Ultrascopic. Allowing for time to dark adapt and a bit of shielding from neighborhood lights, soon saw something almost due west of the primary (and slightly south). In doing so, could just hold a very faint "bluish star" on mild aversion. This in the presence of the perceptibly diminished glow of the 3.9 magnitude primary.

Now I'd seen this sort of thing before. And am always bothered when a faint companion just happens to fall "square" (especially due west) of a primary.

And the usual response was implemented: Up the magnification to verify the find. Something that only seems to work well once I know precisely where to look.

In this case I was again able to "hold" a faint bluish companion slightly south of due west. Now, I've been following this pair on and off for a year now. There have been the the occasional glimpses of something suspicious. But I've never been able to "lock it down". Why might I get an almost definitive view of the faint secondary on this particular evening?

Well, for one, you may note that the "glow" around bright Upsilon-1 was described above as "perceptibly diminished". This in itself is enough to account for success - if indeed success it is. Now all I need due is verify the PA and make a few more visits under "dry sky" conditions...

Typically after a run on Upsilon, I swing due north to the region of M81 and 82. But on this occasion, was thwarted by a bank of high thin clouds sweeping slowly south from the San Jose lightdome region. Fortunately, the bank stalled to the north and instead of knocking off for the night, I sighted on Gamma UMA and resumed the ongoing Spring Galaxy tour.

What follows now are mostly scrubbed notes of that tour taken away from the eyepiece under the soft red glow of the study's overhead light. Despite the use of a red filter, some re-adaptation was required after each return to the scope. The basic method was to turn up a study at 70x then examine it for additional insights at 120. As such, I was operating Argo at exit pupils of about 2.1 and 1.25 mms respectively. Values which approximate the optimal 2 and 1mm values which can be used by most scopes and give comparable views under ideal seeing conditions. (The sacrifice being image-scale - which on larger scopes results in a huge amount of detail being seen that completely eludes smaller apertures.)

Speaking of seeing conditions: At 120x, 3.9 magnitude Upsilon UMA did not display an airy disk, but neither did it defy precise focus either. Meanwhile, 5.0 SAO 28366 (east of Gamma UMA) could be held direct without difficulty. So stability was about 6/10, while transparency approached 5.3ULM in that region of the sky. All of this calculates to a 70x LTM of 12.1 and 12.3 at 120x.

I keep notes like this because I am deeply interested in understanding the precise conditions under which a particular study may be found. The fact is that it is the sky that is the biggest determining factor when it comes to telescopic reach. Many observers are completely unaware that if it were not for the extinction of light caused by the Earth's thick and often turbulent ocean of air, the eye could hold stars down past magnitude 8. Under such conditions, a fine 6 inch scope - such as Argo - might just reveal the 15th magnitude star at center of the Ring Nebula. And this direct with little "eye play".

But such speculations aside, what is it that I saw when limited to some 13 plus magnitudes of averted vision?

M109: An easy locate one 70x field east of Gamma UMA. This galaxy appears a large, sprawling, very faint face-on. At 70x, a starlike nucleus could be held with moderate aversion. Otherwise, this spiral is quite dim, and lacks any sense of frontier. This can be seen as a general tendency to flare to all directions on eye movement (which adds 1.5 magnitudes of reach to my (and probably your own observing) eye. Due to low general (not just average) surface brightness, M109 probably was never likely to have been seen by Messier (or his associate). In fact, as I understand it, the galaxy was a later addition based on an interpretation of some suggestive notes. Overall this galaxy is every bit as difficult for smaller scopes as M98 just west of 6 Coma Bernices!

At 120x, M109 dissolved - with the sole exception of a faint bluish haze around a visibly "smeared" galactic nucleus...

NGC4102: Fellow Astro.Geekjoy contributor theAstronomer turned me on to this galaxy based on a report published at http://community-2.webtv.net/theastronomer/TheDailyObserving/.

And I quote:

NGC4102: Nice spiral!! Caught inside a right angle of bright field stars, the NGC4102 is best viewed for structure with the 9mm. Stellar nucleas, and structure? It's a ring! A dark dust lane completely encircles the center upon aversion, cutting away the arms in what appears to be a ring. And set in the ring is one brigh, beautiful star... Like a cosmic gemstone. But, hey... "Say you don't want no diamond rings..." ;)

Subsequent research (using a Digital Sky Survey image) available through http://www.seds.org/~spider/ngc/ngc.html confirmed the galaxy's "annularity". Of course, I saw none of this at half theAstronomer's aperture, but was pleased just to turn up this 12th magnitude (photographic) 3x1.5 arc minute apparent sized study.

Having so easily found NGC4102, and noting the faint line of sight stars embedded in it, I might speculate (with some reservation) that 4102 may very well be the galaxy Messier actually alluded to east of Gamma UMA - and not the more difficult and sprawling M109. (Keep in mind that without those embedded stars, this 11th magnitude visual galaxy would no doubt have eluded him as well.)

My notes on NGC4102:

"Located about 2/5ths the distance between Gamma and 5th magnitude SAO 28366. Faintish, round, 1 arcminute plus sized spray of luminosity with what appears to be two stars (magnitude 11.5 and 12.5) embedded in it and a third offset by a slight distance. At 120x, the middle/dimmer star seemed to swell in size enough to actually be the galactic nucleus. NGC4102 can be held direct at 70x. Total effect of galaxy and stars makes the whole assemblage much more easily detected."

From NGC4102 dropped five degrees south-southeast to:

M106: No question about this one! Large, bright, well-structured, near edge-on. Spectacular! Starlike core point, bright core, and para-core regions blend off to well defined spiral extensions. The galaxies core point easily as bright as a neighboring 11th magnitude star 5 arc minutes due east. Some softening at 120x, but extensions still perceptible. Oriented more or less north-south shows well defined frontiers to both east and west. A fine 6 inch study even under slightly less than optimal (defined as 5.5 ULM and 7/10 stability) conditions.

The hour was quite late. And I had had enough of disciplined observing. So why not a bit of fun before calling it a night?

M3 was well placed overhead. Easily located, resolved several dozen stars using the "softeye" technique at 120x. Realizing that most globular's are much larger than their obvious core and paracore regions, spent a good amount of time sweeping around looking for dim outliers. But sky transparency supported no more than hints of maybe a dozen such members sprinkled around the cluster well away from its visible frontier.

Not so M13! Though disadvantaged by lower sky position, I was able to hold many dozens of members direct - some across the core. Additional dozens possible well away from the main nexus of the cluster. No sense of "golden glow" or the star-chaining seen under the very best conditions, however.

The view of M13 was good enough for me to take a gamble on turning up its "neighbor" in space: Near edge-on spiral galaxy NGC6207. Picking out this particular mid-11th magnitude galaxy through Argo is usually a sign of good seeing. Despite any doubts, swept a little more than one 120x field north-northeast. And there, in an unexpectedly barren region of stars, caught the faint spray of extinction-level edge-on luminosity. Direct perception of the galaxy caused it to instantly dissolve. Aversion almost gave it a sense of well-defined frontier. - Can't cut it much finer than that...

To finish up, dropped in on Hercules brightest planetary nebula: NGC6210. Small, bright, and highly contrasty, the planetary's disk was obvious at 70x. Made no effort to run the magnification up. That can wait for a better night in its own season...