The Starry Night, 44
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04/05/2010: Spring is galaxy season. I wanted to start much earlier tonight, so I began with RGB images of M81 and M82. I probably need to remove the over-thought-out counterweight on the CCD since it collects the pier when trying to image vertically in the north on the meridian (just where good stuff emerges from Bird Feeder Tree). That forced me to waste about half an hour of decent dark. Low clouds streaming through kept things dicey for a while; I kept the guider's view displayed in a corner of my desktop and took note when it was clear for more than a few seconds at a time. The satellite image was encouraging; all the heavy stuff was blowing off to the NE quickly.
When I finally bagged a streak of six good luminance frames of M81 and M82, I decided to shoot new, better RGB frames, two of each. The result was a little thin, and, well, you know what? Nevermind. There's plenty of time left in the season to collect more and get that field right. On to the next subject for the night...
At midnight:fifteen, I began a series of M106. I'll take more data of the Trio when I can begin a little earlier in the evening. The air is much steadier now, and the point spread function is much tighter than usual. I started a 5-minute L frame for a plausibility check, then shepherded a single cycle of RGB before covering the computer and leaving the telescope to gather plenty of L data on its own. If the sky remains clear, I should get a good run (five hours, six?) before M106 falls much below 45o elevation. The chip is running at -30C tonight, loafing along at 55-60% cooling capacity. Frost is forecast for dawn.
M106 and Companions
M106 and Companions
Sure, I have versions without the nifty faux diffraction patterns, but with so little color data, they're really the only way to get a little life into the scene. I believe the starry condensations in the outer arms of M106 are dominated by bright, blue O-stars, else they're hydrogen-bright HII regions; more color data will tell that tale. I'm sure H-a streamers rise above the galaxy's nucleus. None of that shows up in such sparse color data. I mean, c'mon: 5h 50m of luminance and 15 minutes of color? Next clear night, I'll see about adding RGB. When the Moon gets big, I'll take that as my cue to add H-a.
Clouds on the 6th. So rather that adding RGB, let's withhold it. Here's just the luminance data, 70 five-minute frames aligned, averaged, and stretched, presented "clean" with no color, no shenanigans:
The faintest galaxies in the full resolution version of this image are considerably deeper than 18th magnitude. Guide 8.0 plots LEDA galaxies as faint as that in this field, and those are easy to find. There are many more unidentified, smaller, and fainter ones scattered about. In an inverted, stretched, black on white presentation, they are pretty much eveywhere. 350 minutes on a CCD with a quantum efficiency of 40 - 50% behind a 5-inch glass — you can see things with that.
Incidentally: while working on this, I was streaming "A Clockwork Orange" from Netflix which I hadn't seen in decades (geez, that's a more brutal film than I remembered with dialog I appreciate much more for having read the novel in the interim). I have no idea why I picked that one, of all the available streaming videos, but one nice point: the primarily electronic score is by Walter (now Wendy) Carlos, an accomplished astrophotorographer specializing in high dynamic range solar eclipse photography, a technique she employed long before the imaging world went even more digital than her score. It was nice to "meet" Jonathan Kern on those pages, too, whom I knew for real in Africa half a lifetime ago.
On the 10th, milky skies but some hope. So I uncovered the telescope, sync'ed to the Moon, practiced on M82, slewed to M106 and then tried for some moon-immune hydrogren-alpha data to use for the red channel. The clouds soon thickened to the point that I could often see no stars at all, and even the Moon was severely dimmed. Sometimes only Regulus and one or two stars of the Dipper were visible. The guide camera kept right on tracking on the 7th magnitude star on the right side of the field, and the CCD managed to collect a visible signal from 40 million light-years away. Mind, I have nothing worth using, but this is worth remembering on the night something truly interesting comes along: unless the sky is leaden, overcast may be worth trying to shoot through. See?
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