15th Feb 2024: Astro Pixel Processor 2.0.0-beta29 released - macOS native File Chooser, macOS CMD-Q fixed, read-only Fits on network fixed and other bug fixes
7th December 2023: added payment option Alipay to purchase Astro Pixel Processor from China, Hong Kong, Macau, Taiwan, Korea, Japan and other countries where Alipay is used.
I was stacking a multiple-night project of the Iris Nebula earlier today. Everything looked good, but when I did star removal in Pixinsight, there was this really weird pattern allover the image which kind of looked like IFN, but according to an image-search, I could not find anything similar in other pictures.
Had a closer look at my masters and one of the masterflats looked REALLY weird. Upon closer inspection, I somehow managed to load all the light frames from that session as flats, so that explains the weirdness.I restacked everything using the correct files and now everything looks as I had expected.
Entirely user error, but isn't this something that should have been picked up during registration?
I had 4 sessions, out of which 3 were assigned the correct flats, and one was assigned 69 light frames instead of 35 flats - still it somehow managed to create a masterflat of that session.
This is a question more out of curiosity than requesting idiot-proofing as this was 100% my fault.
For fun. Correct flat on the left, accidental flat on the right.
Hi @wheeljack,
Detection such an issue in registration will be very difficult considering the wide range of data in terms of quality and resolution that used load into APP. I guess it would be smarter to detect this from analysis in the masterFlat somehow.
But, I always recommend everyone to double check data calibration before starting 3)Analyse stars or later. You really want to load some lights in the calibrated view before starting anything I think, you need to confirm yourself that your calibration masters are working as expected. It saves a lot of time and frustration.
Mabula
Aah... That makes sense. Thanks for explaining.
I agree this was entirely user error and easily avoidable, my question was more out of curiosity as in my mind I thought registration of flats would fail if stars were detected in the flats for example.
Hi @wheeljack,
No problem 🙂
as in my mind I thought registration of flats would fail if stars were detected in the flats for example
Flats are never analysed like light frames, we do not check for stars and flats should never be registered in terms of aligning them on stars because the purpose of flats is to correct light frames for illumination problems which represent themselves in light frames on the whole camera's sensor. So the flat frames represent the illumination profile of your imaging setup on your camera's sensor 😉 so we should never apply alignment on flats.
Also, some astrophotographers shoot so-called sky flats, they shoot flats at dawn for instance and these flats work well and can have some stars in them as well which will be gone in the masterflat due to outlier rejection.
Mabula
