M31 - ED80 / ASI1600MM-C

[IanL]

Here's an attempt at M31 done on a couple of nights in December. Framing isn't ideal but I was mainly trying to shake down my DIY stepper focuser. Tried a few new processing techniques including first time with PI's Photometric Colour Calibration process which worked really well. Had a bit of a struggle making the flats for this one - for some reason trying to use the 'correct' normalisation settings in PI lead to master flats with a median that was 1/3rd of the median of the individual flat frames, which then overcorrected the lights. Cannot figure out what the issue is as it has always worked before. Turning off normalisation and just going for a simple average created flats that just about worked OK but I did still have some colour casts to DBE out of the image. Might try a new flats box to see if things improve.

Acquisition: Sky-Watcher Evostar 80ED DS-Pro, Sky-Watcher 0.85x reducer, ZWO ASI1600MM-Cool, Atik EFW2, Astronomik LRGB 1.25″
Mount/Guiding: Orion ST80, QHY 5, PHD2, Sky-Watcher NEQ6, EQMod, Sequence Generator Pro
Processing: PixInsight 1.8.5
Dates: Dec. 8th and 28th, 2017
Lights: L 31 x 300s, R 10 x 300s, G 10 x 300s, B 10 x 300s, Unity Gain, -30C
Bias: 300
Darks: 100
Flats: 30

Link to full size version here (59MB).

Compare to my previous attempt from 2013 using a Canon 500D camera.

[Allinthehead]

Some great detail there. Background looks quite blue on my screen, and also looks like you clipped the blacks. I think you have the data for a cracking image tho.

[IanL]

3 hours ago, Allinthehead said:

Some great detail there. Background looks quite blue on my screen, and also looks like you clipped the blacks. I think you have the data for a cracking image tho.

Thanks - I hadn't spotted the blue cast in the background on my monitor - should have checked the histogram! The black is not clipped just set low per my preferred style, though I have pulled it up slightly. Replaced the original version with the reprocessed one above.

[MikeODay]

Wonderfully detailed image, well done.