Thursday, April 14, 2016

#31 - Thursday, April 14th, 2016

It looked like it was going to be reasonably warm, warm enough that hopefully the telescope would work all evening, so I went out with the goal of imaging M101 and M104.  Alignment went smoothly, although there was a hiccup when the motors moved suddenly while I was starting to polar align on not-Polaris.  But its initial guesses were good for once, and I got it set up and aligned in about an hour.  I started with M101, in the north.  I noticed after a while that the stars weren’t well-formed in the subs, so I re-focused it on Dubhe and went back to M101.  I accidentally left it on 15 seconds after using that exposure time to make sure M101 was centered, so I stacked the 15 and 30 second images together.  They still didn’t turn out very well.  Then I re-collimated, and moved to M104, the Sombrero Galaxy.  Despite getting nice dots on the live view on my camera and well-aligned spikes with the Bahtinov mask, all of my M104 images were still fuzzy, and I couldn’t figure out why.  Despite the bright moon, the images came out reasonably well.  I took a new set of flats and didn’t turn the camera at all during this session, but I think the light source is just too small (the bright white spotlight on the battery) for the size of the telescope to get an evenly-white source incident on the telescope.  So soon, I’ll set it up in daylight and get new flats, and mark the alignment of all of the pieces in the optics train so I can align them the same every time to have matching flats.
M101, Nikon D3100 on my C11, f/6.3 focal reducer 
47x30s & 15s (19m30s total), ISO-3200

M104 Sombrero Galaxy, Nikon D3100 on my C11, f/6.3 focal reducer
26x30s, ISO-3200

The Sombrero Galaxy looks really cool – it’s easy to see the giant central bulge and the thick, dusty edge.  If I can get better focus, this one’s got potential.  M101 turned out dim, but I might be able to get it brighter if I image it on a moonless night and get a good set of flats.

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