Amp glow not fully calibrating out

I should add for all sessions the adaptive pedestal option was selected in calibrating.

I am now trying about half the sessions - some 16 hours of data -in DSS to see if I encounter the same problem

I can report the amp glow appears to be completely calibrated out in the DSS stack.

update- the amp glow reappeared when the stacked image was stretched really aggressively.This was the case with the APP stack as well, though it was much worse with the APP stacked image

any suggestions? Thanks in advance

@seeker372011 Hi Narayan. It sounds to me as if the darks have not been taken properly. There are some sensors that are notorious when it comes to amp glow, making it very hard to remove it. Let me know if you would like me to have a look at your data to see if I can give you some tips. We have a server where you can upload the data so there is no need for you to upload them to a cloud storage of your own.

Yes please it would be great if you could have a look.

as I said DSS is removing far more of the amp glow than APP- so I am not entirely sure the problem is with the darks. The DSS result is almost - but not quite - perfect

Shall I upload a few lights and a few darks  - maybe one from each session?

@seeker372011 I would need a few of lights, darks, flats and either bias or dark flats (or both) depending on what you use. You can upload to

https://upload.astropixelprocessor.com/

with username and password: upload

Create a folder called seeker372011_amp_glow and put the files in there. Let me know when the upload is done by using the reply link under this message so I receive an email when you reply and I will have a look asap. Thanks!

@wvreeven, I just uploaded  a few lights, darks, flats and dark flats to a folder named as you suggested.

I also uploaded a stretched image which shows the remnant “starburst” amp glow on the right hand side, which is the problem I am struggling with.

thanks so much for offering to assist, I really appreciate it

@seeker372011 I first integrated the session 1 lights and I think that I may have seen a little amp glow on the right border. It is hard to tell with only three lights. Then I integrated the session 4 lights and I saw no amp glow at all but I did see a satellite trail. Then I integrated all lights together and I think that the amp glow may have returned again. Once again, only a few files so it is hard to see if it is there at all. Here is a screen shot of the last integration:

How do you integrate all sessions? Do you create integrations per session and then integrate those together again? Or do you load all data into individual sessions and integrate them all into one result? Or do you load all data into one session and integrate?

@wvreeven in this case I loaded all the lights, darks, flats and flat darks each as a session- so nine sessions. One calibration and integration.

would it make sense to integrate each session separately and then register and integrate all the sessions?

@wvreeven ps yes that is most definitely the amp glow - the starburst..gets worse when all 196 odd frames are stacked

@wvreeven ps yes that is most definitely the amp glow - the starburst..gets worse when all 196 odd frames are stacked

@seeker372011 I don’t think that integrating them separately will make a difference. Do you see the amp glow in each of the nine session integration results?

@wvreeven thanks for the response. I haven’t tried integrating sessions separately- but will try a few sessions chosen at random and see if it is in all or only some and report back

thanks for your support 

@wvreeven I just checked a few individual sessions by stacking them separately 

I found the amp glow in all but a lot less in last years sessions compared to this years. The difference was in the spacers I used- this years is supposed to be optimised to manufacturer recommended 55mm last years was a bit off

I also checked data collected with another CMOS camera- same chip but colour - on the same object taken this year and using the same telescope etc…and found amp glow.

went back and checked data collected with the same camera but another telescope - a REdCat instead of an ED 80- and found zero amp glow 

so it appears Prima faci the problem is with this particular imaging train…for some reason with same gain offset and exposure duration the amp glow is calibrating out in one imaging system- the RedCat - but very poorly in the other.

the only other difference was in the duration of the flats- with the RedCat I used 1.71 seconds with the ED80 I used 2.7 seconds, ( using the Flat Wizard in NINA) 

this is getting weirder and weirder 

I am getting a new flattener for the ED80 today as my current reducer/ flattener is not giving me a flat field to the edges, Could this help? Who knows but I will try and see what results- and report back in case it is of interest or help to anyone else

Any suggestions advice will be most gratefully appreciated 

Dont know when I will next get clear skies of course!

@seeker372011 I would be very surprised if the reason for residual amp glow were the flats. As a matter of fact, I redid the integration with your session 1 files and this time NOT using flats and I still see the hint of amp glow in the result. So I am pretty sure that the flats are not the cause.

Have you tried integrating the RedCat files once more with the APP version that you use for processing your Helix Nebula pictures? If you did, do you still see no amp glow in the result? That could be a good check to verify that the likely cause is in the imaging train.

@wvreeven

yes I did exactly that

i pulled out old data- August 2021 - and used the identical AAP settings on both the old data from my other telescope and on the new data

no amp glow in the old data, amp glow that appears in stretched images in the data from the telescope I am currently using

it just doesn’t make sense! But .. the problem seems to be with the current optical system

and of course the more you stack the worse the amp glow gets 🙁

my AstroTech flattener has arrived. Hopefully some clear nights next week when I can test

if that fails I will be completely bereft of ideas!

@seeker372011 Fingers crossed for clear skies then. And that the new flattener solves the amp glow issue!!!

I have the same issue - residual amp glow after stacking. I'm using a ASI183 MC Pro camera, which has significant amp glow. Other pertinent items:

1. Tried stacking with just darks and also with flats - no significant difference. 

2. Tried different gain values and exposures - no significant difference. 

3. Adaptive pedestal setting was turned on. Small improvement, but still residual amp glow is visible in stacked (and stretched) image. 

4. Using ASIAir, which doesn't allow changes to the offset. According to the FITS header, offset = 10. 

5. Comparison of FITS headers on lights and darks show identical temps, gains, offset, etc. 

Any suggestions for me to try? 

Thanks, 

John

Hi

i don’t really have a silver bullet to offer, I am sorry. I stopped using that ED80 and have since had no trouble with my other telescopes - RedCat 51, Samyang 135 and very recently a Sharpstar Z4.

I have the same camera as you do - in QHY ( mono) and ZWO ( colour) flavours. I use both NINA and ASIAIR depending on which imaging camera.

so I think I can conclude the issue is  not related to 

a- the camera

b- AAP

c-the acquisition software

But something to do with my darks and flats

one thing I did find with the ED80 - especially with the ASIAIR- was a material amount of light leakage from the focuser end when taking both darks and lights. ( I shoot these on the morning after, on the kitchen table in daylight/ or with kitchen lights on- light box ( home made) for flats)

I found it necessary to completely cover the focuser  and the end cap with black material- I used an old stocking of my wife’s wrapped around the focuser  and then some other material on top and that helped. ( for darks and flat darks)

as I said I have sort of stopped using this ED80 pretty much so don’t have anything else to offer other than looking at your darks and flats and how you acquire them