Difficult background extraction

[LorenzoM]

Hi, I stopped for several month from astrophotography but now here I am starting with RGB imaging for the first time.
I decided to try with NGC6914, reflection nebula in cygnus and acquired 12 images of 10 minutes for each channel, no L data yet. The telescope is a FSQ106 coupled with sbig ST2000XM camera.
Unfortunately data have been acquired close to street lights and a green gradient appears. I tried to remove it with background extraction but I have not found a way yet to do it in a successful way and gradient persists also after correction.

I am not very good with this tool so please can you give a look?
If you want please continue also with image processing up to the end, but post here the result and passages if you do it; it is my first RGB.

Thank you for your help.

Here you can download the data https://www.dropbox.com/s/hfforxys1kjam8e/rgb.rar?dl=0
Each channel has been calibrated with flat and dark and registered to each other.

[msmythers]

Hi Lorenzo


Let me explain what I did. First I combined the 3 images with ChannelCombination. Then I applied STF unlinked. I then used AutomaticBackgroundExtractor(ABE) with the settings shown in the image below. This was just a very quick look. I'm sure others can get a better background. I have not done anything else to the image at this point.


Mike