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2023-09-28: APP 2.0.0-beta24 has been released !


Improved application startup, fixed application startup issues, upgraded development platform to Oracle GraalVM JDK21

We are very close now to  releasing APP 2.0.0 stable with a complete printable manual...

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[Solved] Flats

3 Posts
2 Users
Molecular Cloud
Joined: 4 years ago
Posts: 2
Topic starter  

Hi all,


I can kick myself for not being consistent in AP and after near a year I decided to get back into it.

I have taken M101 over the last few nights using my rig (ODK 14 inch which has corrector, and in-between I have a filter draw to mount my square LP filter followed by G4 16000 CCD and with all the filters.


I have dumped everything into the latest software of APP and left every at default and began the process, something which has worked well for me in the past. 


For some reason I am seeing terrible indented flats being applied at the final stages on process. 


After speaking with the staff who made the camera ADU should be around 30K with exposure 4 - 5 seconds 


My dark frames at 10 mins each  

Lights at 5 m each 

Bias 0s 

Flats 5s


I have tried without the dark and bias frames and getting the same result. My darks and bias frames are from February this year btw. 


When I am creating a master light frame and stretched I cannot these large bunnies!!  So I'm a little confused...


I have only taken my flats with SGP Pro, the rest was with voyager software. 


m101 Luminance session 1 session 2 St


I'd love for someone to shed some light! 


Since this post I cleaned all the filters and I must say i didn't see much dirt at all!! 


Thanks in advance. 




P.S I have just stacked the lights only and darked the image via levels in PS.. Dam there is alot of bunnies 




This topic was modified 4 months ago by JAspal Chadha

Universe Admin
Joined: 6 years ago
Posts: 5701

I would start with not taking the bias at 0 seconds, up that to about 0.5 seconds per frame as some sensors have issues in the fastest speed range (signal not being linear). I would also advice to take your darks at the same settings as your lights, also exposure time wise.

Molecular Cloud
Joined: 4 years ago
Posts: 2
Topic starter  

@vincent-mod thanks I think I resolved the issue  as the main problem was the LP between in the optical train 


Nothing to so with dark or bias on this occasion as without them it was still noticeable.