More APPM Results -- Can Someone Help Me Understand This?


Running an APPM session with a f/10 (native f/15 with 0.67 focal reducer) Cassegrain on an 1100 using an ASI1600MC-Cool. Image scale is 0.26 but because this is a OSC at Ray's suggestion I used 0.52 for both X and Y scale. Other settings were generally standard except the max catalog magnitude was reduced to 12. (This seems to avoid a lot of checkpoint timing errors.)  This was during a half-moon almost directly overhead. Not ideal conditions. A bit of wind. I can't figure out how to manually set temperature, pressure and humidity so the default of 10 was used when it was closer to 18.

The run on the east side made sense. Most errors with a couple of dozen arcminutes. 

Things went crazy on the west side, reporting pointing errors of 10 or 15 degrees!

I installed this model and then pointed in the west and did a plate-solve and recal and got an error telling me the platesolve-based correction of 15 degrees was more than the maximum allowed. So something is wrong here.

The physical setup of the telescope on the mount seems appropriate -- for sure no 15 degree misalignment in orthogonality. The primary mirror is fixed. Collimation is good -- checked a week ago. The polar alignment is good -- ran a session with Polemaster yesterday and checked with RAPAS today.

Am I missing something obvious here?


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