Added twice as many frames as normal – still noisy. Probably need longer exposures. Bad gradients needed a lot of work in APP.
UPDATE: Used the demo versions of TOPAZ DeNoiseAI and it makes a huge difference. Removes noise without removing details. Other de-noising seems to just blur features – this is far more intelligent.

Object IDM101, NGC 4321
DetailsSpiral galaxy, Ursa Major
Mag. 9.5
Size 7.4’x6.3′
Telescope250mm f4.8 Newtonian
CameraAtik 460EX @-15C
Exposure(s)20x180s each RGB
darks, flats, bias
CaptureAPT
ProcessingAPP, Photoshop