Cocoon - wide field (reprocessed star field)
Although I quite liked the result of the Cocoon nebula I didn't like the resultant starfield, so I decided on a reprocess in an attempt to improve the starfield. I noticed two defects - 1) Quite a few of the stars where not uniform in colour. 2) A few seemed quite bloated and devoid of colour.
Going back to the FITS files for the stacked and calibrated data, I noticed that the average FHWM of the individual RGB channels varied quite a bit. I presume this is mainly due to the inability of my scope to focus the light rays of the individual RGB channels to the same point. I attempted to correct for this by performing a devolution on the individual channels such that the FHWM where very similar. After alignment of the deconvolved RGB channels, the result was a much more uniform star colour.
To reduce the effect of bloating stars I decided to perform a starfield specific DDP streach in CCDstack and paid attention to only the starfield bit map values, I adjusted the DDP values such that the maximum bit map value was less than 200 (allowing me to subsequently colour stars the stars). I then blended the starfield image with my previous Cocoon image via PS masks.
Whilst not perfect, I think the result is a significant improvement in the starfield quality.
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