Hi Monte
I’ve not measured any drift due to Polar Alignment errors. However, here is a two pane composite image I took recently, showing some offset between the first (red) image (03:15am) and the final (blue) image (05:11am) some 2 hours overall.
The EM200 was only polar aligned with the PAS, using the XLS spreadsheet to provide the alignment data.
- The FOV is approximately 26x17 arc mins.
- On my screen, I measure the 17 arc min dimension to be approx 130mm.
- The difference in registration of the stars over 2 hours is approx 5mm on the same screen.
- So, in 2 hours, the drift = (5x17)/130 = 0.65 arc min.
Hmm, that sounds too good to be true though?
Cheers
Dennis