M101 da Monteromano.

[pk825]

Poi mi spieghi l'errore in elaborazione
Visto che hai fatto molte pose, con dithering immagino, potresti utilizzare la tecnica Drizzle di integrazione:

The Variable-Pixel Linear Reconstruction [1] algorithm, better known as drizzle, was originally developed at the Space Telescope Science Institute to process Hubble Deep Field images. Drizzle is an algorithm for the linear reconstruction of images from undersampled, dithered data.