Is SGP compatible with Pinpoint Platesolver (I have assumed the answer is yes)? How are the Rotator rotation angles defined in SGP? Is NCP up or down? Is East left or right? Is CW positive or negative? Does rotation direction need to be manually switched after Meridian flip? I am using a C14 EHD on an AP1600GTO-AE mount with a Litecrawler focusser/rotator (that works like a champ) with an ASI6200MM Pro camera. All hardware is working properly. I need to understand how SGP uses data from the Rotator and the platesolver. Is Postion Angle the same as the SGP Sky Angle? Are the SGP angle conventions those defined by the IAU? I have been unsuccessful in making a single 2x2 mosaic (many many terabytes of data and hours used).
a log file will be needed to troubleshoot.
SGP supports both the free and paid Pinpoint.
SGP uses the rotation angle provided by the driver. I’d guess most people put the rotator on the scope so 0 degrees mechanical is at the top of the scope or at the “top" of the chip. I try to get it so 0 degrees sky angle is as close to 0 degrees mechanical as possible. I think it’s basically impossible to have 0 sky and 0 mechanical match for every object. In my experience, the sky angle varies a few tenths of a percent.
East on the left versus right and North up versus down depends on your scope and the number of mirrors it has. See your scope documentation.
I believe “Position Angle" is whatever type of angle you requested - either Sky angle or Mechanical. SGP gets the mechanical angle from the rotator, since that’s all it knows. A plate sove is needed to get the Sky angle.
Do the IAU position conventions state that 1 degree is rotating to the right or left of 0? As far as I know, SGP simply report the angle it’s told, so your last question is probably best answered by the rotator manufacture or whoever wrote the platesoving software. I wouldn’t worry about IAU. All the astronomy software work together when rotating, so they’re all talking the same language, or know how to convert if there is more than one language.
What is the problem you’re trying to solve with answers from these questions? To be honest, I’d guess most people would answer “who cares?”. If you want east on the right in your images and it’s on the left, flip the image. Ditto for up/down.
For manually switching rotation direction after a flip, my AP 1100GTO-AEL mount doesn’t need it and I suspect all AP mounts are the same since they use the same firmware and software. But to be 100% sure you’ll need to try it.
I’ll answer a couple of questions in general, not specific to SGP: See the ASCOM Master Interfaces doc for Rotator, and its associated FAQ What are the Angles that Rotator uses, and How Do They Relate? The diagram you see may help. NCP is up, north, in Equatorial Coordinates. Equatorial Position Angle increases Counter Clockwise from Equatorial North. Do not reverse the rotator once you have it set for CCW as viewed from behind the camera. It’s always CCW for PA. You can roll the rotator over 180 deg on a flip if you want your images to be right side up regardless.
Thank you very much for the input. That paper was the basis for my questions relative to SGP. I was trying to figure out the SGP rotation convention. My main issue was getting ‘eyes’ on the rotator in my observatory while I checked movement (avoiding snags and collisions). Through trial and error I think I got it. Thanks again.
To answer other questions specific to SGPro
Pinpoint is the standard we use for coordinates. Other plate solvers return solves in different (not incorrect) coordinates or systems. SGPro normalizes all solves from all solvers such that they are presented in equatorial coordinates. In other words, Pinpoint is the only solver that does not undergo any kind for normalization after solve so, in a way, it’s “the most” compatible with SGPro.
Yes, otherwise known as PA and MPA (which we should probably change), Positional Angle is the Sky Angle and Mechanical or (Mechanical PA) is the absolute position of the rotator.
If you’d like to share additional data and or logs we can help troubleshoot… there are many reasons this can happen.