The Starry Night, 119

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5/8/2014. During its brief intersylvan transit, Mars offered no joy, but since the 'scope was focused and the night steady, I wanted to shoot something. I spent an hour or so the last time out refining polar alignment, and I wanted to try it out, but I suspected that at least one drive gear needs remeshing, so I wanted a subject which would not require guiding. Put it all together and it's time for Messier 3. Moonlight? Piffle. No guide stars? Who needs those?



145x30s Clear + 5x60s RGB
(1h 12m 30s + 15m total RGB)
Flats, but no darks and no guiding.
(Click for higher res, please!)


I saw several frames with PSF's in the 1.7 arc second range (superb for here) and eccentricities in the sub 1% range (excellent for anywhere). I had a great pile of luminance data, so I tossed the bottom third. The rejected frames included some with PSF's over 3 arc-seconds and eccentricities of 30% or more (not shabby, just not up to tonight's snuff).

I'm never satisfied with my efforts at M3. I always want to recapture the view through the 26-inch Clark at Leander McCormack Observatory (U of Va, May 1973). This image is a little too blue; the huge yellow giants are OK. And I always ended my public star tours at Chaco Canyon by aiming John Sefick's donated 25-inch Dob at M3 and inviting unsuspecting guests up the ladder to have a look. It was a good time to be alert, because some literally gasped and stepped back into open air. I'd urge visitors to refocus for their own eyes, and when I was confident they had the cluster shining at its best, I'd quietly say, for each, "The faintest stars you can see in that cluster are a thousand times brighter than the Sun." That was probably stretching it a bit; 250 times would be closer, depending on how acute the visitor's vision was. In the photo above, the faintest (and I mean the very faintest) stars are just about as bright as the Sun, 19th magnitude to a fair approximation.


5/9/2014. This morning, I remeshed the gear and worm that drives the declination axis. It's been overshooting when making small corrections and amplifying rather than reducing some guide errors (errors of a few tenths of an arc second often get blown up to an arc second or more, sawing back and forth past the proper spot). When I realized what was happening, I rechecked polar alignment and then turned off guiding, letting the telescope take data without corrections.


7/8/2014. As you can tell from the timestamps, the summer haze is upon us. Short, muggy nights mean sungazing season is here. That part of the Slow Blog is seeing at least some action.

It's also time to put the RV kit together. I am cleaning up the G11 and completing its kit with an eye toward using it with a DSLR and either the 5- or 6-inch refractor. Bigger glass can wait. I've cut some long Losmandy legs down to 24 inches (the short ones I am using here are 18 inches).

I bought a used STV to guide the G11 and a used Kendrick power pack to power the mount and the guider. I've just ordered a 50w photovoltaic panel, a charge manager, and some wiring with which to ease into the deep pool of solar power. This small outfit should suffice to keep the truck battery charged in my absence; to help the house battery through trips to the boonies (more watts and bigger batteries would be nice for that, but this is a start); and to let an 18AH Kendrick power pack drive the mount and STV forever. Together, the G11 and STV should drain a fully-charged pack in 9 hours, more or less; the 50w kit should bring it back from the dead with 4-5 hours of decent sunlight (which is not asking for much in its intended venue). On cloudier, dimmer trips, I can draw from the house and truck batteries when really needed. A cooled CCD and a laptop would require significantly more juice; solving the power problem for guided DSLR imaging Out In The Dark is a dress rehearsal for more ambitious productions to come.

I've spent more than I would like, but it had to be done before committing to dark sky adventures and also in time to work out kinks. It's always better to solve problems in the back yard rather than in the back of the beyond.

We've also begun revamping the interior. The slab table is in place (not 100% perfectly yet, but close enough to use); we've discovered how to remove window treatments in favor of bamboo blinds; storage options begin to take form for the front right space; a custom privacy curtain is up; additional accent pieces and wood for a fold-down desk are en route.




Except where noted, deep-sky photos are made with an SBIG ST2000XM CCD behind a 10-inch Astro-Tech Ritchey-Chretien carried on an Astro-Physics Mach1GTO. The CCD is equipped with Baader LRGB and 7nm H-a filters. The internal guide chip of the CCD most often keeps the OTA pointed in the right direction (I'll let you know when a Meade DSI and a separate OAG or guidescope takes its place). Camera control and guiding are handled by Maxim DL 5.12. The stock focuser on the AT10RC has been augmented with Robofocus 3.0.9 using adapters turned on the lathe downstairs. Maxim performs image calibration, alignment, and stacking; Photoshop CS4 and FocusMagic 3.0.2 take it from there. Gradient Xterminator by Russell Croman and Astronomy Tools by Noel Carboni see their share of work, too. Beginning in May 2013, PixInsight has taken over some of the heavy lifting for transfer function modification and deconvolution.


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                   © 2014, David Cortner