Last night it was Schröters Valley. There, I was reminded of a Spielberg movie of decades past now "touched up" and probably playing at a theatre near you. For in the sketch at left you may make out the smiling face of the film's central character.
Special Observing ReportBackyard Boulder Creek: March 25&26, 2002
It's Been Awhile
Opportunities to observe the last several weeks have been "catch as you can". The few occasions when the sky presented well conflicted with other "higher priorities" like traveling out of town. And sometimes conflicts occured with actual higher priorities like making music with the Quintet. (Yes, it's true, playing jazz takes precedence over observing in this man's life...)
But last night was different. Last night I got to observe through a truly "awe-ful" sky. But I observed anyway. And things were much better than they appeared...
Variable thin clouds laced the night sky. Not the kind of clouds you "suspect" as being up there. No, the 75% Moon took care of that! No suspicions at all. There were, in fact, times when even Luna herself was visibly beset. At best the pale overcast would thin enough to show only a ghostly, luminous ring of faintly prismatic colors surrounding her gibbous orb. Once the 80mm was turned on that dread Luna however, she transformed into the lovely and beguiling Selene. For you see, although the air lacked transparency, it was still. Only the vaguest "quiver" of Selene's limb could be seen.
Of course at 11 days, Selene is not at her best. This is the woman who has returned from a long day at the office and shows for wear. Too much of florescent lights shining down through "glass ceilings" perhaps...
But there is always something to attract the eye to such a woman...
Last night it was Schröters Valley. There, I was reminded of a Spielberg movie of decades past now "touched up" and probably playing at a theatre near you. For in the sketch at left you may make out the smiling face of the film's central character.
Of course, having recently re-re-re-re-re-collimated the Pup, had to stop bye and seek Plato's council. (Two brightenings at 140x.) Spent some time casting my eye over the rest of Selene's bounteous form. Always get a huge kick out of Clavius and that cochlea of descendingly sized craters (beginning with Rutherford) that arc so gracefully across it's girth. Tycho definitely sports rays. Gassendi captured my eye - for awhile. Then it was off to the Gas Giants.
Jupiter now descends but lies in the sky's middle third. The view at 140x was extraordinary. Cleanest, most obvious view of the rift in the SEB seen yet. Belt edge irregularities along the NEB (especially toward the EZ). NTB, a nice thin contrasty line paralleling the NEB. And above that a faint, but fully resolved NNTB. On the other hemisphere and above the SEB, the STB revealed only a well-defined northern frontier. Image scale a bit small at 140x - so dropped in the 10mm 3x / 1.8x barlow eyepiece series (220x). Everything still there. Amazing, for you see 210x is 7/10 stability magnification through 150mm Argo. Pup! You done good - but you owe a lot to the sky. Nice lazy, slowly wafting first diffraction rings seen around mid-range magnitude stars (3 to 4).
Saturn sinks fast. Even so, Cassini graced the ring system with a nice black pencil line. Titan trailed to the east. The planet's yellow-white "cumberbund" quite distinct - but no southern frontier to the SEB. Popped in the 43mm aperture mask. Yep, one and change inches of aperture can reveal Cassini - but it probably would never have been discovered at that aperture. There's just too little of Ring A visible to make a high contrast view possible...
The rest of the evening was given over to duplicity.
The Castor pair is astoundingly beautiful - especially at 43mms. Huge, perfect, and unequally-sized airy disks. At 140x the gap between stars about the size of the secondary's disk. At 80mm, the gap expands to something larger than that of the primary. But now two unruly diffraction rings appear rather than the single perfect one visible at 43mm's. With double's, "less is more". Happiness is seeing two almost touching airy disks. Sure you are only seeing a diffraction effect, but it is so easy to imagine the sun's themselves. Come on refractor manufacturers, make that adjustable iris-based aperture-stop!
Took in two more pairs before knocking off:
Xi UMA. Nice clean resolve at 220x. Secondary leading - as I recall. Dropped down to 140. Thin hairline split. 120x: A peanut. Sky tranparency maybe 3.5. Seeing 8/10. Makes for a nice 80mm test using sepCalc. Running the numbers (primary magnitude 4.4, secondary 4.9) gives a calculated separation of 2.1 arc seconds. - very close to the "published" value of 2.3.
Iota Leonis: At 140x I "suspected" a teardrop disparate with secondary leading and to the north. 220x still only suspected. Nothing definitive. At around 1.5 arcsecs, this disparate may belong to Argo. It's 1.75 arc second published separation seems a bit too generous to my eye...
Knocked off around 9:30. Hoped to rise before dawn and visit with Summer's Skies. During the course of the night, clouds must have thickened. But last night will hold me over - at least until tonight...
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Sky is Sky
Luna approaches fullness. And tonight Shickard's immense walled plain was the seat of sustained interest. Stretching some 200 kilometers in breadth and hugely foreshortened, the plain appeared peppered with fine features. A real treat, and one to take especial notice of during future "near full term" observing sessions...
Schröters Valley again caught my eye. This deep serpentine gorge remains well-chiselled despite the overpowering presence of bright, cometlike, Aristarchus. In fact, all the great ray systems were well evident this evening: Tycho, Enche, Capernicus, even the twin-tailed Pickering-Messier "Bird of Paradise" complex on Selene's evening-side.
Truly, the Moon through 150mm Argo presents all the detail any Selenophile could possibly crave. But the view earlier in the evening afforded by the Pup failed to slake my eye. Certainly the 80mm achromat was disadvantaged by low Lunar sky position. But it is my experience, that there is a world of difference between the sub-2-arcsecond resolution offered by 80mms compared to that of a sub-one arcsecond instrument. The Moon, like Gas Giants, and Mars is Argo's special reserve...
As suggested above, the evening's adventures began with the Pup. By 7:30, the sky was as dark as it was going to get (under the circumstances). As Luna ascended, things went from bad to worse. Complicating this was the lack of the kind of superfine stability seen the previous night. There was a "fuzziness" about mid-magnitude stars that said "7/10 seeing". Diffraction rings lacked precision while tending to chaotically shift and brighten. Not a good night for doubles. Disparates lost to moonshine, and closely matched pairs to sky instability. The Pup could not resolve Theta Auriga, nor Alnitak. Rigel's blue gemlike companion went unseen. Only four stars possible in the Trapezium. But, despite the Moon, I could still descry the Eagle's Wings embracing the Great Nebula.
The sky was fine enough however for open clusters. Started with Procyon. Dropped south to brightly scattered M47. Then east to that faint, dense, dusting of stars known to us as M46. Ran the Ultrablock filter over the cluster looking for Planetary NGC2438. Had better luck turning up the brighter, more concentrated planetary NGC2440 further south. Suspected at 48x, the planetary became almost obvious at 80x. Use of the filter made it obvious. Bright star with small, faint, hazy mantle.
Continued further south to M93. The best of the lot this evening. Looked variously like a "Lazy X", "X-wing fighter", and dragonly. Two dozen plus stars apparent. Made a sweep southeast for nearby Bright Nebula NGC2467. Even with filter - nada. Back up to M93, and five degrees west to h3945. Found a group of about half-dozen stars compacted into a two or three arcminute region. Not sure if this was the Herschel group, but whatever it was made for a better open cluster than several of the 60mm MAC studies turned up in Auriga last month!
Everything to this point was all stargazing...
Now for the test of the evening. Given the Moon's fullness, and general brightness of the sky, wanted to see if the 80mm Pup at 48x (1.7mm exit pupil) or 150mm Argo at 70x (2.1mm exit pupil) would give a better view of M81 and M82. The thinking was that the fast achromat should give as contrasty a view of the galaxy pair as the slower Mak. The fact that the achromat was wielding a slightly smaller exit pupil offsets this BUT, given the brightness of the night sky this too might prove an advantage.
As one might suspect neither scope gave particularly good views of the two galaxies. More elliptically presented M81 was an easier find than edge-on M82. Chiefly because of its bright central core. To my eye, the edge fell to Argo. A good test for this was whether or not nearby galaxy NGC3077 could be found. Since I knew precisely where to look, I made short work of finding it through Argo. But here the achromat stumbled a wee bit - requiring eye movement to hint at it while Argo held it continuously under moderate aversion.
So like other tests along this line, Argo has proven a slightly better "deepskyer" than the Pup when exit pupils are closely matched. This now also appears to be true when the sky is beset by stray light or poor transparency.
Hmmmm...
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