Strange Gradients, can anyone advise?

[Jkulin]

I have been trying to grab sufficient M109 data, and have grabbed about 85 x 300sec subs from each channel, I have tried new flats every time and processed each night separately just in case there was any gradients through the moon etc.

Last night the moon didn't rise until 03:30 and as since the 26th April when I started it has been virtually at the Zenith.

The filters have been cleaned and cleaned and they are exceptionally clean.

Does anyone think it could be the desiccants could be the cause?

The camera is a Moravian G2-8300 MKII and I have had it nearly 2 years.

Just really lost with this, no settings have been changed and none of the optical chain has changed, so would welcome anyone's thoughts?

[Jkulin]

Just to add, my good Mate suggested that it might be diffraction spikes from the nearby star Phecda, so I grabbed the view from CdC and from the SGP framing Wizard and it would appear to be a very plausible reason, what do you reckon?

[RayD]

@Jkulin I reckon he could be right, John.  I had exactly the same using my FSQ106 in Spain when there was very light (almost unnoticeable high cloud) and imaging a specific target.  Slewed to a different, relatively close by, target and artifacts went.  

Edited May 12, 2020 by RayD

[Jkulin]

Cheers Ray, with two of you saying that then I do trust your opinions, so that means I have to use it as it is then or clip the black to get rid of it!

I checked the desiccant and they weren't bad, they were translucent whitey orange and they should be bright orange, so they are cooking at the moment!

When I first started this object on the 26th I thought got to be the moon and retried with 4 lots of flats and four attempts at collecting Lum data it has produced the same results, can't be the moon or any light pollution so unless the camera has a problem it can only really be that.

Ta Ray.

[Laurin Dave]

Hi John...  I did M109 recently and whilst Phecda was off the camera sensor it was still coming in the telescope and causing a bright glow... I'd guess the same thing is happening to you 

Dave

[Jkulin]

Brilliant (Literally) thanks Dave, so what did you do...embrace it and include it in the image or scrap it?

[Laurin Dave]

It was just a rather large glow in the corner...  but it had me wondering what was wrong.. it looked like ASI1600 amp glow on steroids (and was in an identical place) a dose of closely spaced DBE points removed most of it..  and some Photoshop tricks the rest.   I guess with your scope the light is reflecting off the secondary vanes,  I'd just live and see what you get with it as your data looks good. Is it in an identical place on all your stacks?  if not then maybe you could try making a pseudo luminance and see if the rejection algorithm helps mitigate..   Also if you did reshoot then rotating the camera would put the glows in a different place, which again may help ..   Lovely target.

Dave

[Jkulin]

Cheers Dave, Yeah I tried a selective DBE and it didn't want to play ball, it is on the other bands as well but no where near as bad.

I did think about making a pseudo Luminance and then custom address it as a flat, but I was worried that it might take too much detail.

I'll have a play and see what I can come up with, if it doesn't come out too bad then may leave it in there to help others with the same problem.

I've got so much data on this now and with the short nights and little sleep I'm shattered, so it might have to wait until it comes round next time.

Thanks for your help.