Does this BPM look ...
 
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The problem with the data upload limit for attachments has been fixed. I have restored it to 30MegaBytes. A recent forum software upgrade was responsible for the changed limit. Please accept my apologies for missing this when upgrading the forum sofware, Mabula.

Does this BPM look right?  

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(@biggen)
Molecular Cloud Customer
Joined: 3 months ago
Posts: 4
18/06/2019 2:58 pm  

The tutorials are a bit out of date as far as the GUI layout but I think I followed it closely enough.  I'm just generating a BPM here and not any other Master Bias frames so I took very long darks specifically for this (600s x 30 subs).  I also then took 50 flats and then 50 dark flats as well.  I had detect bad columns enabled and left at their default values.  Hot pixel kappa was at 2.0 and Cold Pixel % was at 50.

Bad Pixels are at 19%, Hot Pixels are at 13%, and Cold Pixels are at 5.5%.  Does this look right? I'm using an ASI294MC Pro which seems to suffer from amp glow looking at my individual darks.

 

Here are my raw darks, flats, and dark flats.

https://www.dropbox.com/sh/h1tuxqrusb939tc/AADDqZXyvmxjIQTef-u3yXlca?dl=0

https://www.dropbox.com/sh/mtr1h3ppfeae14v/AABRzTvM_7tBkid5i-zyNj9sa?dl=0

https://www.dropbox.com/sh/yj5qxavty0rs21p/AABBI2oNK2UWKSkn2irKC5_ja?dl=0

 


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(@vincent-mod)
Galaxy Moderator
Joined: 2 years ago
Posts: 596
18/06/2019 3:05 pm  

Yes, sorry for the older GUI tutorials, they could benefit from a refresh (and a write-up). Anyway, a BPM uses the darks and flats, don't correct the darks beforehand as that would defeat their purpose for the BPM, you do need bias or darkflats loaded for the flats sorry. Plain, raw darks and good flats (showing a histogram at about 50% in the linear phase(!), I find SGP doing a nice job with that using the flat-wizard). If those are good, you should have a very nice BPM to be used for (potentially) months/years.

I gave your BPM a look, left part looks good, right part seems very odd. Don't have a lot of time atm, but will have a look at your darks and flats and see if something is up, I'll recreate a BPM from those to see if I get the same.

This post was modified 2 months ago 3 times by Vincent Groenewold - Moderator

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(@vincent-mod)
Galaxy Moderator
Joined: 2 years ago
Posts: 596
18/06/2019 3:58 pm  

Yes, similar result. I also checked the "reduce amp-glow" setting, I did get the amp glow in the bpm now. But do you really have so many bad columns in the right hand part of your sensor (don't really see it in the darks)? So maybe this has a weird effect in the bpm creation, I'll tag Mabula (@mabula-admin).

This post was modified 2 months ago by Vincent Groenewold - Moderator

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(@biggen)
Molecular Cloud Customer
Joined: 3 months ago
Posts: 4
18/06/2019 4:04 pm  
Posted by: Vincent Groenewold - Moderator

Yes, sorry for the older GUI tutorials, they could benefit from a refresh (and a write-up). Anyway, a BPM uses the darks and flats, don't correct the darks beforehand as that would defeat their purpose for the BPM. Plain, raw darks and good flats (showing a histogram at about 50% in the linear phase(!), I find SGP doing a nice job with that using the flat-wizard). If those are good, you should have a very nice BPM to be used for (potentially) months/years.

I gave your BPM a look, left part looks good, right part seems very odd. Don't have a lot of time atm, but will have a look at your darks and flats and see if something is up, I'll recreate a BPM from those to see if I get the same.

Thanks for that!  I didn't do anything to the darks, flats, or dark flats.  I simply loaded them into APP.  I didn't use any outlier rejection at all.  Kept everything default until I got down to the BPM kappa/bad column detection settings.

I created the flats using the APT (Astro Photography Tool) CCD Flats Aid.  I told it to aim for a 20000 ADU target.  With the ASI294MC Pro, there is an internal calibration issue taking images under a few seconds so I made sure to dim my light panel enough to get the flats in the 6.5 second range to hit that 20000 ADU target.  With the dark flats I just repeated the plan but covered the scope.

None of the video tutorials I've seen mentions to use the bad column detection so I don't know if I should have enabled that feature at all.  Every thing I've read said I should aim for a hot pixels to be less than 3%.  Mine seem way above that.

This post was modified 2 months ago by Biggen

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(@vincent-mod)
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Joined: 2 years ago
Posts: 596
18/06/2019 4:07 pm  

Yes, it seems odd there would be so many. it might be that the amp glow throws this detection off. Could you try without detecting bad columns? If that looks more even, you can give it a go on some lights to see if it corrects hot- and cold pixels properly (I tested on a few of your frames and that indeed works better).

This post was modified 2 months ago by Vincent Groenewold - Moderator

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(@biggen)
Molecular Cloud Customer
Joined: 3 months ago
Posts: 4
18/06/2019 4:28 pm  
Posted by: Vincent Groenewold - Moderator

Yes, it seems odd there would be so many. it might be that the amp glow throws this detection off. Could you try without detecting bad columns? If that looks more even, you can give it a go on some lights to see if it corrects hot- and cold pixels properly (I tested on a few of your frames and that indeed works better).

When I get home today, I'll re-run it without the bad columns detection and see if that makes a difference.  Hard to believe a 2 week old camera would have so many bad/hot pixels/columns.


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(@biggen)
Molecular Cloud Customer
Joined: 3 months ago
Posts: 4
18/06/2019 9:20 pm  

Well I re-ran it without bad column detection enabled and it looks a bit more "normal".  As in, it looks like everyone else's.  I played with the hot pixel kappa setting between 2.0 and 3.0 but it does little to change the amount of hot pixels detected.  It's showing around 8% hot/bad pixels now.  No cold pixels.

I'm assuming there is an issue using bad column detection with my particular setup.


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(@vincent-mod)
Galaxy Moderator
Joined: 2 years ago
Posts: 596
20/06/2019 11:06 am  

I don't think so, the BPM is likely fine now and can be used to get a lot of the hot pixels out. I would still use darks (with column detection) to further improve the correction with your data.


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