wipe issue

[Burly]

hi ivo could you cast an eye over this file M27 i have had flats issues of late which i think is resolved image has been cropped and binned but i cant seem to rid a cloudy cast from around rh side of m27 could you have a look and give me an idea as to what the issue may be .
https://drive.google.com/file/d/1Vcj4l0 ... sp=sharing
m27 approx 3hrs dithered subs at 180 sec iso200,,nikon d5300 SW 200pds, baader CC ,no lp filter stacked in DSS, 25 flats and 25 flat darks stacked in dss
Edit. seems issue still being caused by my Flats after stacking lights only seems the EL panel is heading towards the bin and a new light source required image of lights no flats or bias
https://www.eastmidlandsstargazers.org. ... ext=widget

m27 lights stacked only in DSS https://drive.google.com/file/d/1_px_oI ... sp=sharing
dave

[admin]

Hi Dave,

I could not readily spot an issue in the very first link, but happy to have a look if you're still hunting for the issue.
If still needed, would you be able to just share a link to the dataset(s)? (the two Google Drive links don't work and ask for log in, then permission requests)

Lovely image by the way!

Cheers!

[Burly]

Will do ivo , it’s probably something I’m doing so need to get to the bottom of it.

[admin]

Thank you for sharing that dataset.

Something has indeed introduced very fast undulating gradients. The top two possible causes are usually #1. incorrect flats or #2. optics dewing over at some stage during acquisition.
Masking out the M27 (thereby protecting it), and using a very high Aggressiveness will take care of the issue nicely, but it is of course preferable to treat the root cause.

[Burly]

Thank you for your time Ivo I will up the exposure of flats to 1-2 secs something someone told me to do with El panels, which I think is the issue I will update if I manage to get to the root cause .

Regards Dave

[Burly]

I’m hoping flats issue is solved after taking 2sec subs , 1.5 sec subs were the same but 2secs seem to work better I could tell using the auto stretch in APT that they looked better, I will keep my eye on it but the usual method of setting Av mode gone right out the window using an EL Panel others I know say they use longer flats with El panel .