I'm tired of dodging trees, let's aim at something overhead. The Pinwheel Galaxy...

December 8-9. The weather tonight, to quote the sage of Glade Spring, is colder than a polar bear's nose. We're headed for a low in the middle teens. The battery pack insisted it had zero charge all morning and then suddenly snapped to "all lights lit" "ready for anything" status. I charged it for the rest of the day, carried it outside, plugged in the rig, verified polar alignment, sighted in Messier 33 (it was clear in the 9x50 finder; this is a very transparent night), and turned everything on at 7:00 PM. I was imaging ten minutes later. So far so good. The computer reports corrections are mostly of sub-pixel magnitude. The spiral is vivid on the guider chip with 5 second exposures, less so on the 200mm through the Ha filter, which I am retaining for the sheer crispness of the stars.

I set up a sequence in Maxim to capture 15, 10 minute exposures while we watched a Christmas movie ("Moonstruck" of course). I came downstairs to find the telescope still tracking nicely, working the 14th image of the series. I uploaded all the images, tossed a couple of images with problems, replaced them manually, and then shot a series of frames with the autoguider to run out the battery.

3 hours and 20 minutes after I turned the powerpack on, I lost the ability to communicate with the camera (when the voltage dropped below the SBIG's minimum operating range). Air temperature was 33F at the start, 22F at the end.

I'm not especially pleased with the processing. Or with the data for that matter. Focus was just a bit off (hence the over aggressive sharpening), and 200mm isn't enough focal length even for such a relatively big target on such a relatively small chip. I'll revist the data with more care eventually, and I'll revisit M33 with more glass.

Now... how to get a signal to and from the notebook at the top of the driveway? A directional wifi antenna would have problems with the many trees and if sufficiently directional to deliver decent strength would be too directional to let me set up whereever I want up there. So maybe an ethernet wire threaded through the woods and coiled up at the verge?

I found an attractively priced 56AH AGM battery that could be coupled in parallel to the existing battery through the external posts or mounted internally as a replacement for the 40AH battery (which would become the aux). Assuming that 3.3 hours proves to be typical with the present battery, then the 56AH upgrade would yield 4.5 hours. The two batteries in parallel would provide power for right at 8 hours. I suspect that using the Canon as my imaging camera will cut power consumption by 50% -- 6.6, 9, and 16 hours respectively.

Even 96AH will allow just one night in the field with the cooled CCD if I don't have some provision for recharging. Day trips to the parkway, OK, but on longer trips Out West, I'd still be dependent on AC outlets. Enough photovoltaic power to recharge a 96AH stack in one day would be pricey. A small generator would do it, but if you're going to use a generator, why not just use a generator in the first place? (Granted they are less obnoxious devices by day than by night, so maybe the trick is to shoot at night off batteries and charge by day off the generator.) Let us think about this some. I do not like burning gasoline to run a telescope; hours per gallon is not a dimension I want to consider.

Tomorrow I'll repeat tonight's experiment to see how consistent the runtime is. When I'm sure I have a grip on how long things will operate set up this way, I'll try powering the ST2000XM through the DC posts instead of through the Xantrex's inverter.

The Pinwheel Galaxy, Messier 33 in Triangulum
15x600s, 200mm F2.8, H-a filtered, ST2000XM @ -35C,
darks applied, sigma summed, stretched
like mad, and cropped.

 

Reversed to show all those lovely
H-II regions to best effect.

 

What the guider sees: 5s, Meade DSI, Orion ST80.
What's with the triangular stars?
3-point rings pinching the lens cell?

 

 

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Text & Photos by David Cortner
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