Confused, flat was rotated 180 deg

After many many months of being “out of it”, I finally got the scope back out last night. For shake-down I setup an auto run on M15 and went to bed.

This morning I’m working in PixInsight to see what I got, ran the lights and flats through the weighted batch processing script, and low and behold the master flat came out rotated around 180 degrees from the master light (I’m only doing the Blue filter subs for the moment while I work out the kinks). I don’t remember ever running into this issue before. If you flip the flat around the dust motes line up perfectly.

Has anyone run into this before? I must have completely reverted to Noob status in last 6 months or so

I think I have come across this in regards to darks… I recall you can select somewhere a checkbox which allows for auto-rotate of images after meridian flip. I leave this unchecked now as I prefer to have manual control…

Thank’s Kevin, sounds right (that I missed a checkbox). Though I wonder if this has to do with the same PixInsight problem that I have run into before. Namely that Pi only checks FITS keywords for “standards” that they recognize, and no others. So for example if you shoot a series of LRGB images, Pi will not automatically recognize the FITS keyword that Prism writes into the FITS files to determine what filter and other image attributes. It’s annoying for sure, but there are workarounds. I just wonder if there is a FITS header item that tells if an image is pre or post meridian flip, and if so I wonder if Pi is ignoring that one also…

well, that is the catch. I shoot and pre-process the frames in PRISM for the sole reason that it knows where the coordinate (1,1) is and flips the frames to match. Perfect every single time

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Yea I’m going to adjust my thinking and start using Prism for the pre-processing I think. I’m thinking the post stuff that most people use Photoshop for is what I will use prism for (hey I spent this money I should use it)

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look man, PRISM is all about simplicity and rotated cal frames drove me mad before.

might even include some advanced BPM and rejection algorithms in V11…just saying :smiley:

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I’m starting to think that “dropping out” for a while made me forget more info than just not knowing stuff from when I was starting out! LOL