The Starry Night, 127

:: home ::




              <<  83  84  85  86  87  88  89  90  91  92  93  94  95  96  97  98  99  100  101  102  103  104  105  106 
              107  108  109  110  111  112  113  114  115  116  117  118  119  120  121  122  123  124  125  126  127  >>  SRCH

10/30/2014. "In a dark time, the eye begins to see" (Theodore Roethke) Some obscure details in a familar target begin to emerge when I get the processing close to right. I aimed the 10-inch Newtonian at M31 the other night when the sky was clearer than usual. I'd had the G11 up in the cul de sac for solar photos earlier, so I mounted the Newtonian on the A-P Mach1 for the night. That didn't hurt, but given the lovely performance of the STV guider, I'm not sure it helped all that much, either. I used the Canon 6D to take 180s exposures for just under three hours (54 subs). When I first processed the night's take, I thought 180s might be too long for my skies, but it turns out I just made a mess by using too few darks. I shot an additional 45, 120-second darks night before last and then, during Game Seven of the World Series, I had the computer use them (and a set of bias frames) to recalibrate and recombine the long, clear subs. Here's a pretty fair look at what I got:



10-inch F4 Newtonian with Baader MPCC-III on Mach1GTO
Canon 6D, 54x180s @ ISO 1600 (55°F) 2h42m total
45, 120s darks, 8 flats and 8 bias frames
50mm guide-scope and ST-V
Click for a remix with more aggressive PixInsight work.

Nevermind. I'm not happy enough with this yet.

Of course, I want more. More exposure, better skies. But for the moment, I am delighted by every aspect of this: the camera's sensitivity, the optics' performance, the drama-free performance of the ST-V guider, and PixInsight's tools for stacking data and displaying a wide dynamic range. I've got sharp stars, details in the core together with those streaky dust lanes marbling the sky, all with good color and tones. I am just a little skeptical about the diffuse glow in bottom center, what I think may be light from M31's halo. At first I thought it was an anomaly from a bad flat, but then again, those dust lanes have to be silhouetted against something, and the extended fan of light just might be real. Anyway, the leftside of the histogram just doesn't seem quite right.

All in all, I think the kit is almost ready for the road. A few loose ends: two 12v adapters are on the way for my and Amy's computers. While using the G11 with the Latitude D820 for solar imaging day before yesterday, the battery once again began to crap out early. I hooked up a small inverter and ran it and the G11 off the Kendrick battery pack long enough to take some images of huge AR2192 rotating off the disk, but it was clearly an inconvenient and inefficient kludge. (Worse: seeing was so dreadful that even stacking thousands of frames didn't produce a good photo.)

[One clear night at a time, two maybe three per month... it's taken almost a year to get from here, "almost ready for road," until the kit is ready for the road. What would I give for reliably clear, dark skies? Almost everything. 9/22/2015]


10/31/2014. The 12-to-19.5v notebook computer power adapters arrived very quickly; they work like a charm on the Dell Latitude (used for telescope- and CCD-control as well as for solar video collection), and they should work just as well on Amy's and my Inspirons. That's one more step toward making the RV a self-contained office and observatory. Splitters for the hand control and guider are also here, but they have not been tested for fit and function. They should make guiding and fine-tuning my aim less of a hassle. The digital timer and 12v power splitter are also here; they'll require some wire-cutting and planning (not in that order) before helping to manage overnight runs.

I suffered a shower epiphany last night: I was thinking about putting a goto system or at least DSC encoders on the G11 to help place faint targets (and targets in awkward or star-poor parts of the sky) on the chip. Then I remembered what the "SC" in "Digital Setting Circles" stands for and realized all at once that I can use my plain old analog setting circles to get into the ballpark. I've never used them, but those archaic, almost steampunk, engraved circles are not there just for show. We're not talking about the 2000mm R-C and a fingernail-sized astronomical sensor. The 1000mm focal length of the 10-inch Newt feeding a 35mm DSLR combine for a field measuring 2° x 1.2°. Between that and the ~3° finder field in the ST80, I can surely find just about anything on the first or second try. Right? Right?

There's snow in tonight's forecast. Clear weather should return the next two nights, but the Moon will be awfully bright.

11/02/2014. Done and [finally] done. The 12v power timer is ready to use. So is an auxillary port wired straight to the battery terminals on the Kendrick power pack. The latter should let me supplement the internal battery with a second source connected via a Battery Tender connector. No! I should be able to charge it from the solar panels, any 12v outlet in the van, a dedicated charger, a second battery, etc. [As a quick measurement seemed to confirm and as Battery Tender docs do confirm: polarities will be reversed when connecting one battery to another battery using their quick connect cables -- just don't do that. At least think it through and try to make a foolproof version. I could use the cable that terminates in clamps, for example, and be damn sure to reverse the clamps. Or make up a custom widget with otherwise unused termination (Australian or European or otherwise unconfusable ends). Or, or.... better yet, just don't. Use a second battery on its own, not routed through the Kendrick box when more AH's are needed. Put a 22AH inside the case and use the new 17AH one in there now for the G11. Or use something smaller for the G11 alone and mess about no more with the perfectly useful Kendrick. Back to the drawing board on that wild hair.] Now, as for the timer:




Know what's really scary about that photo? I've been talking about making such a power controller for four years! It took $25 and 25 minutes and it looks as if it will work great.

I adopted this practice from astronomical antiquity: I set the timer's clock to mark days from noon to noon rather than midnight to midnight so that there'll never be any fussiness about zero hours when setting start and cut-off times. E.g., if you want power from the start of an imaging run at 10 PM until 3 the next morning, just set the timer to be on from 10:00 - 15:00 on the current day. Don't mess with weekly or daiily this or that, just call up timer #1 (of 16), set the times, set mode to "auto," and go get some sleep. This widget can be inserted anywhere downwind of a 12v power supply -- the Kendrick for the G11, the Pyramid for the A-P.


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.


:: top ::



                   © 2014, David Cortner