Andromeda Galaxy (m31) revisited and recaptured.
My first astrophotography target was Andromeda Galaxy as well, and the date was 02 October 2022. But wanted to improve the details and color of M31 capture by prolonging the imaging time, since I live in a relatively larger city with its fair share of light pollution. I believe I have made a stride in improving the imaging results. The reasons for improving is obviously more imaged data, newer dual narrowband filter Optolong L-Ultimate, and newer software improvements with Pixinsight Plugins BlurrXterminator, Generalized Hyperbolic Stretch, Spectrometric Color Calibration.
Recapturing dates were 17, 18, 19, 20 October 2023. Not all these nights were cloud-free. Have to admit quite a few of my images were thrown out due to clouds. However, I could save a total of 778 images of 2 minutes each for a total of almost 26 hours of imaging time.
Capturing and Processing Summary:
William Optics GT81 IV with 6AIII 0.8 reducer, ASI2600MC Pro CMOS camera, Optolong L-Pro and L-Ultimate filters, ZWO OAG with ASI220MM Mini guide camera, ZWO AM5 mount, ASIAIR Plus.
For processing, I have used Pixinsight, Adobe Camera Raw, Topaz Studio.
Optolong L-Ultimate dual narrowband filter contributed vastly for bringing out the red nebulosity of Andromeda galaxy.
Combining L-Pro and L-Ultimate data was done this way:
Processed L-Pro and L-Ultimate data seperate with DBE, SPCC, BXT, NXT.
Separated L-Pro and L-Ulrimate stars by StarXterminator.
Then Split the channels R, G, B. Did Linear Fit of the individual channels with the corresponding R channel. Then from L-Ultimate data took only R channel afterLinear Fit to corresponding L-Pro R (throwing out G and B). Then added 0.5XR of L-Pro to 0.5XR of L-Ultimate. Then LRGB Combination without the L component, with chromium noise reduction turned on.
Next proceeded with the combined L-Pro and L-Ultimate data with GHS, Curve Transformation.
Last added stars from the L-Ultimate data to the combined image.