Hmm, where might I ...
 
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Hmm, where might I have gone wrong?  

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(@rickwayne)
White Dwarf Customer
Joined: 9 months ago
Posts: 10
November 24, 2019 05:00  

Here is a screenshot of an integration done from two sessions. Camera was rotated between the sessions but they were otherwise identical -- optics, exposure, gain, filter. Processed in APP in multi-session and mosaic modes, I get this. You can see where the screaming amp-glow of the 183 sensor is very well calibrated out in the angled frames, but not at all in the ones that are oriented horizontally. (Note the characteristic starburst on the right, but also the glow along the edge that so effectively highlights the seam between these imaging sessions!)

Obviously I need to throw this integration away, but then what should I do differently? I don't want to just compose two separately-stacked images, since I'll lose the SNR boost from stacking in the overlapping section.

Thanks for your help!

Screen Shot 2019 11 23 at 9.46.16 PM

 

This topic was modified 3 months ago by Vincent Groenewold - Moderator

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(@wvreeven)
Neutron Star Customer
Joined: 1 year ago
Posts: 131
November 25, 2019 11:32  

@rickwayne

How did you process the two images? Multi-band processing? Multi-session processing? It looks as though the darks were only applied to one set of the images and not to the other. I *suspect* that you assigned your darks only to one session and not to the other but I cannot be sure unless you tell us exactly how you produced this integration.

 

Wouter


(@rickwayne)
White Dwarf Customer
Joined: 9 months ago
Posts: 10
November 25, 2019 17:28  

Yes to both -- multi-session, multi-band, since I also had OIII data (but only for one session). It's possible that I would have neglected to assign the darks but I would surprise myself if so: I'm perfectly aware of how critical darks are for the 183! I have a vague recollection of only being able to assign something to one session, when I wanted it to go to more than one and thinking "Huh, that's funny". So maybe that was it? Or maybe I was trying to assign the OIII data to both sessions, which makes no sense but that's never stopped me before.

I know Mabula strives to make APP pretty idiot-proof but I'm a particularly determined idiot. Part of the problem here is that I was running this off frames stored on my NAS instead of on my computer's local disk, and so every step took so long that I'd pretty much forgotten the details of the preceding one by the time I was setting up the next.

I'll try it again tonight and report back. Thanks!


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(@rickwayne)
White Dwarf Customer
Joined: 9 months ago
Posts: 10
November 27, 2019 00:23  

I still see a little bit of difference in how the two sessions calibrated, but it's like night and day (OK, given the "sunburst" amp glow that's a really terrible pun). I actually don't have darks at exactly the right temperature so I used some that were done about 5℃ warmer. That would certainly make it hard to get all the amp glow out, but I only see it on one of the sessions, not both. Still, it's a ton better, so I must have neglected to assign the darks to both sessions the first time around. I also added bias frames this time, which may have helped a bit, and I don't think I put in the flats that I did in the first session.

Thanks for the help in tracking down my mistake. All in all, it's a much, much better result, and I can easily crop out the remaining glow.


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