Feature request: Flats vs Rotator position

I recently started using a camera rotator. When I use a new rotation angle I need to generate a set of flats for that angle.

The ultimate dream feature would be for SGP to add a flats target to my sequence for each rotator position that I used in the sequence. The flats target would set the rotator to the appropriate angle and have an event for each filter that I used at that angle. (this would be a cool feature regardless of rotator – automatically generate a flats target based on the filters used by the lights targets.)

I realize that is a lot to ask for and I’m going to have to manage my flats manually for the foreseeable future. To that end I have a much simpler request: please record the raw rotator position in a FITS header when saving an image. If I can look at the rotator position fits header, I can have enough information to generate my required flats. SGP currently records the camera angle, but that is not the same thing since 1) the camera angle is some fixed offset from the rotator position and it is difficult for me to recover the rotator position from the camera angle, and 2) after a meridian flip the camera angle changes by 180 degrees but the rotator position does not change at all; I can’t distinguish a meridian flip from a rotator 180 degree rotation (both give the same camera angle, but the rotator move requires new flats while the meridian flip does not.)


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I’m moving this to “Accepted Unplanned”. It will require a much needed overhaul of the flats wizard that is smarter about scanning and using existing targets with light frames.

In the meantime, with 2.4.1 and above, you will be able to find the rotator’s uncorrected position angle in the FITS header “POSANGLE”.

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Hi Ken, Thanks for considering it.

I am running and my FITS headers have ANGLE but no POSANGLE. Is something wrong here?


Nope. It will be in the next beta. (soon-ish). Just made the changes a few minutes ago.

Great, thanks!