Gear
Nikon D3500
Samyang 135 mm f/2, Manfrotto tripod
Images
630 light frames @ 2 sec at f/2, adjusting the camera every 100 frames or so, that M31 stays in frame
60 flat, 60 bias, 60 dark
Processing
Stacked in SiriL with this guide https://pixls.us/articles/processing-a-nightscape-in-siril/, only set star threshold to 2.0 instead of 1.0
Crop to remove non-overlapping regions due to lack of tracker
Green noise removal
Color calibration to set black and white point
Auto histogram stretch
5x contrast-limited adaptive histogram eq. tile size 8, clip limit = 1
Background removal in PS by healing brush M31, dust and scratches at 200px, apply image blending = difference
2x radial gradient in LR: 1 for M31, 1 inverse for stars. Boost saturation of M31, remove stars by editing exposure of the inverse radial gradient.
Single 2 sec frame below
