I’ve started a multi-night project for M51. July 28 was the first chance to catch Luminance data, 1.5 hours so far (in 5-minute subs). Sky-glow is fairly bad in this part of the sky (removed manually in the attached shot), and will require some careful processing as I get more data.

A satellite trail wasn’t completely removed via the median-combine. Once I get more exposure time, I’ll probably just discard the frame with the satellite.

Update: Problem in Colour Darks

I’ve had a couple of evenings chance now to gather colour data, and have captured R, G, and B, all binned 2×2, on separate nights.  I was quite disappointed with the results – all are showing nasty black blotches. Looking for the cause of this, I believe my 2×2 calibration dark frames are faulty (I keep a library of darks at different reference temperatures and different exposure times, and think my 3-minute, -15 degree darks are bad).

It’s supposed to be cloudy for a few days now, so this will be a good chance to take new darks, then test those against the acquired data to see if that was the problem.