I'm not sure what you designed your mosaic like, but I would guess that one of the following is your issue:
- Bad parameters for camera FOV (sampling or pixel height/width)
- Capture rotation not matching "planned" rotation.
My honest guess would be the latter, but without knowing how the mosaic was laid out it's hard to know for sure. Also selecting a guide star shouldn't matter much as the slew/center step has already completed. So unless you had PHD slewing around for a while trying to lock you should have been pretty close. Especially since your FOV looks pretty wide.
Thanks,
Jared
