This is another one I captured back in November, but am just now getting to process. I like shooting this galaxy as it is quite bright and fits in my current field of view pretty well.
It is 2.7 million light years from earth and part of our local galaxy group (also includes our own Milky Way and Andromeda galaxies). It is 60,000 light years across. It’s also interesting as data captured in Ha narrowband reveals similar star forming regions to our own galaxy, but with a unique perspective from outside looking in.
I captured this in RGB with an additional Ha layer mixed in as additional red. The component channels are shown below:
m33 – blue channel 
m33 – green channel 
m33 – red channel 
m33 – Ha channel
The imaging session details are below:
| acquisition date(s) | October 5th, 2020 November 13-14, 2020 |
| imaging camera | ZWO ASI 1600MM Pro |
| guide camera | ZWO ASI290mm Mini |
| mount | Skywatcher EQ6-R pro |
| telescope | Explore Scientific ED102 APO |
| flattener | Stellarvue 0.8x flattener and reducer |
| exposure settings | gain 139 exposure 180s camera temp -20c |
| stacking | 31 lights – Optolong 7nm Ha 21 lights – ZWO Red 21 lights – ZWO Green 21 lights – ZWO Blue additional calibration for each channel 30 darks 30 flats 30 dark flats |
| processing | PixInsight 1.8 |
| astrobin |  |
To do the HaRGB combination, I first created the RGB with pixel math and made some adjustments before later adding the Ha channel into Red. The initial RGB image is shown below:
The next step was to layer in the Ha channel using the PixInsight script for NBRGBCombination. After combining and doing some additional contrast boost and saturation enhancements, I did a final crop. The final image is below:
For comparison, here is a similar framing I shot about a year ago using Canon T3i DSLR:
m33 – RGB Canon T3i DSLR m33 – HaRGB ZWO ASI1600