The annual M42 this year is a mosaic with the Running Man. APP dealt with the gradients really well after messing with the Normalisation and Integration parameters.

Object IDM42, NGC 1977
Telescope250mm f4. Newtonian
CameraQHY168c @-15°C
Exposure(s)10x180s each pane, 2/10
Darks, flats, dark-flats
ProcessingAPP, Photoshop, Topaz DeNoise AI


Mosaics in APP – defaults unless otherwise stated
1. Load – all as normal – you don’t need to use separate sessions for each frame if you did it all at the same time
2. Calibrate as normal
3. Analyse stars – I needed to increase from 500 or it wouldn’t work – went 1400 – might have been the subject but I suspect it helps to stitch the mosaic together
4. Register – Registration mode – mosaic, use dynamic distortion model, uncheck same camera and optics (will be suggested if you don’t)
Scale stop = 1 (for a 10% mosaic overlap)
5. Normalize – Mode – advanced – neutralize background
LNC degree – 2nd degree, iterations 3
6. Integrate – Enable MBB – 10% because I did 10% overlap in the mosaic
INTEGRATE – and if you’re lucky it all works