Koehler Urban Astrophotography

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 fr