Now that I've spent a few nights gathering data after months of, well, not... I'm more inclined to try and get to the bottom of my recent elongation issues. Looks like there might be some clear sky time tonight but with a moon phase of 57% I'm thinking I should give imaging a miss and try and get to the bottom of my most recent star shape issues.
I expected that I was going to find the primary was stuck to the cork pads on the mirror cell again and freeing it up would fix it, but that turned out not to be the case.
Can someone confirm my plans for diagnosing make sense:
- Confirm problem exists in short unguided exposures; if not it's tracking/guiding related
- Assuming not tracking/guiding related, rotate the camera. If the orientation of the elongation stays fixed with relation to the image produced by the camera, it suggests collimation and/or tilt
- Assuming it's not collimation/tilt, rotate the primary mirror. If the orientation of the elongation changes, it suggests primary mirror astigmatism, if not, it's the secondary
Not sure if I'll need to recollimate after rotating the primary, which I can do without removing from its cell. Probably will, but it'd be better if I didn't have to, because that way less things are being changed and I'm more likely to find the cause...