Fixing Flats on CHI-1-CMOS

[Liam Quinn]

I've tried everything in WBPP with both Calibrated and Raw files - the images attached is from processing the Raw files (the resulting master from 25 odd subs and the Master Flat) 
Almost sure this is an overcorrection from the flats - not sure what the solution is but I cannot get a solid image out of the Adv Request I put in (which was a lot of my credits). 

It could be the wrong offset values for the dark frames and flat-darks resulting in a too large numerator in the flat field correction - could be an incompatibility with identical settings in different acquisition SW - I have no idea if different software is used or not. 

Ernesto mentioned the following in the PI thread -  " It is possible that this halo in the OIII files is an artifact caused by this automatic calibration. Have you tried doing manual calibration using the raw frames and calibration files? " 
I have gone through a whole raw WBPP production pipeline and still no joy. 

I think the auto cal files are also off due to the flat file somehow.
Anyone wants a quick sample to try and stack O3 without major issues in WBPP here you go
(I know it will not image solve with this few subs but thats a non issue)  -  Test O3 Data with Relevant Master Files  

Having read anything I can regards this kind of flats issue - the only other thing I found was this comment
"Looks like it's the QHYs fault. It has two read modes: one for long exposures, and one for shorter exposures. These do not match properly, and thus causes the flat to fail. It can be fixed somewhat by adding (rather than subtracting) a pedestal to the flats."

If it an issue with the flats file - can it be address and would I then be OK to process my data?
Would the calibrated images in my data archive - auto refresh with the new flats?  -  Do I have to fix from the raw files on updating the flats?

As of right now I'm sat with a lot of data I cannot use as I get dust rings and nasty corners.
Reggie Jones mentioned synthetic flats buts its not going to cut it sadly.

 

 

[Liam Quinn]

Just to close the thread - I sorted this after a lot of help from TL staff and support. I stopped using the supplied Master files and created my own in Pix from the raw calibration frames - worked much better.