This image was a difficult one.
It is the first imaging project with my new wide-field rig consisting of a Sharpstar 130 f/2.8 hypergraph and a ZWO ASI6200MC Pro camera. The Spaghetti Nebula (SH2-240) fits nicely into the FOV but is a very faint object. Thus I tried to collect as much data during this season as possible, without attempting to first optimize the setup (the backfocus is not yet perfectly dialed in). Unfortunately the weather conditions were mostly poor, the moon and clouds and dust reduced the quality of the data considerably.
When stacking the whole data I realized that asteroid (9) Metis went through the FOV in a sequence of nights begin of Februrary, leaving some ugly stacking artifacts behind. Due to its slow motion and appearance in hundreds of subframes, the statistical pixel rejection in the stacking algorithm was not sufficient to eliminate it completely. So I had to remove it from the subframes before stacking, which then again led to stacking artifacts. Luckily I found that these remaining stacking artifacts were completly removed by drizzle integration.
Processing the cleaned stack again took many attempts as the OIII data still remained weak. Therefore I went for a more artistic processing to bring out the contrast of Ha and OIII instead of sticking to the results of the photometric color calibration in PI.
Hope you like the result!
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