North American Mosaic - NGC 7000 - Processing

In processing frames for each of six panels making up a 2x3 mosaic of the North American nebula from the venerable Orion CN10, noted rotation across subs and imaging sessions... which is exacerbated by poor guiding with elongation in stars.  Despite efforts at drift alignment to gain good polar alignment, serious issues remain that complicate / frustrate processing to integrate subs into specific panels... with some sessions working out better than others.

Wondered if the alignment of the guide scope with the OTA is critical... since these are definitely now far off each other (several degrees at least).  Noted this link describing the likelihood of rotation if polar alignment is not perfect for this case.  Fixed this in later collections to ensure nominal alignment between the OTA and the guide scope.

Also noted that the camera was not rotated on the OTA to be in line with the collection plan.  This resulted in a failure to co-register all the frames due to lack of overlap.  

The frames collected up to 10/09 plotted in Aladin:

Frames for the NGC 7000 Mosaic collected through 10/09/21. Note the initial issue with the camera rotation (adjusted in subsequent sessions).


Using the ST80 field of view as a background allowed the frames to be crafted into an initial mosaic.  Bayer drizzle in Astro Pixel Processor provided the combination of the Canon T3I with the venerable ST80 with a pixel pitch of ~1.1"/pixel... which is actually finer resolution than the 2x binned data from the CN10.

Initial mosaic of CN10 frames up to 10/09 over top of an existing ST80-collected NGC 7000 integration.

After the tenth imaging session on 11/10/2021, Aladin was used once again to plot the imaging footprints for all collections resulting in this map:

Frames for the NGC 7000 Mosaic collected through 11/10/21. Note the persistent gaps despite working to rotate the camera field of view.

This illustrated the additional collection would be needed to fully cover the nebula.  :<

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