Dear ALL,
I was wondering if anyone would like to take a stab at processing my Barnard 150 data (~12 hrs of data; SNR is low due to short subexposures of 10mins). Despite having correct star colors, my sky background is not correct. I have attached a link to the files, and included my own processed version. In my processed version, I managed to get a proper sky background color, but for some reason I cannot seem to replicate the results starting from scratch (I wanted to reprocess the data again and add a few tweaks). I'm thinking that the incorrect color background is coming from improper use of DBE/ABE. However, after DBE/ABE is usually do a superbias on the image to check the gradient. To me it looks fine. The LRGB files have already been calibrated, registered, subframe selected, and drizzled. No cropping or DBE/ABE have been performed. I'm really struggling to find out where I am going wrong. If you could please provide a detail processing outline, it would help me very much. Just for reference this is the processing approach I have taken:
Link to files:
https://www.dropbox.com/sh/lblrjrkg1blhjen/AAB7Pyze8G54zsys2lGkd7sYa?dl=01. Image calibration (bias, flats, and darks; flats using a flat pannel), subframe select, registration, and integration all channels. Drizzle applied.
2. Dynamic crop images
3. Apply DBE/ABE (bg subtraction) - I check the bg model, and sometimes run a superbias on the resultant image to confirm proper gradient removal.
4. Linear fit - fit to the brightest channel
5. ChannelCombination
6. Bg neutralization
7. ColorCalibration - for the white reference I use the entire image and enable structure detection (6,1). - At this point the star colors look great but the bg color does not.
8. Masked stretch - 100 iterations or more
9. Nonlinear stretch of Lum data via histogram transformation.
10. LRGB combine L with RGB.
11. Various curve transformations using in combination with range selection masks.
12. Finish off with TGVdenoise.
As mentioned my first attempt at processing this object did produce correct bg sky color. But, I can't seem to duplicate the results. This is driving me nuts! I would really like to see what other pixinsight users would do, and hopefully find out where I am going wrong.
Thanks for your help!
Vik
