Stack Multiple Gain sets
Stacking program, astrometric (plate) solver, fits file viewer
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han59
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Can you stack multiples data sets using different gains? And get them to sync with the correct darks etc? Been working on SH2-132 the Lion and just realized that some of my really good data was taken at a different gain setting. Hate to throw it out.
That is not good. I have had the same issue once and throw a part away.
For mono image, In principle you could stack in seperate blocks. So stack the lights with a dark having the same gain. Then you could combine two results by stacking the two in mode average. ASTAP will combine them in ratio using the total exposure time recorded. But there the gain will make problems. The influence of the larger gain series should be reduced accordingly. In principle you reduce the recorded exposure time in ratio with the gain. I could automate that in ASTAP since the gain is normally in the header.
For colour it becomes more complicated. Autocorrect of the colours should be switched off initially.
The process is never tested. I have no problem to look into your series series if it all can be automated.
Han
Automating it would be great. I shoot almost entirly Mono. I do not have a complete data set on this object yet. But have subs for each. Want me to upload it somewhere for you?
Yes upload all files somewhere. With all files I can properly check the results.
e.g zipped at https://ufile.io/ or share a file on google drive.
Here is a link. This has lights for S H and O. Some of the H data is in 139g and some of it is 300g. I attached master darks for 139 and 300g. I did not do any flats yes as what is mainly the issue is the darks. https://www.dropbox.com/sh/hefssu7s929x32v/AAAajHjMzBgMzwlspoByGlWOa?dl=0
Check this in 25 min from when I posted it. Servers says 25min till all of it is uploaded.
I'm playing with the data. Good for testing but the master darks are missing. Can you upload them as well?
The final test should be an improved SNR of a reference star or maybe better the limiting magnitude of the H-alpha stack.
Han
I will upload a new version in a few hours. The weight factor seems to work good. If the H-alpha images are stacked with a weight factor related to the gain, then the limiting magnitude increases from 16.6 to 16.8 which is a 1.2 times improvement.
Version 1.0.0RC11 is released.
ill downlaod and try it . Did you find the darks? They were in a folder.
The darks folder was emphty. Testing with darks will probably not make a difference but I like to keep the set for future testing. If you can send a link to the darks that would be helpfull.
Somehow ASTAP is never finished. I think I move to version dates rather then version numbers :)
https://www.dropbox.com/s/0tvieghtb61pfqy/master_dark_137x300s_at_-30C_2020-11-15.fit?dl=0
https://www.dropbox.com/s/5fq1iankqouj6x2/master_dark_89x300s_at_-30C_2021-11-06.fit?dl=0
Sorry I am so long in fixing this. I uploaded the files. Must have stopped last time becase I ran out of space or something.
Did you get to try these Han?
Yes i have downloaded them and stored them for future use. At the moment other priorities :)
I am looking for the option to stack with different gain sets and do not see it. What part of the interface it it in?
That is done fully automatic. Same as with exposure duration. The pixel values are normalised using the gain and their influence in the stack is proportional to the exposure duration.
Ok maybe it did not work becase I only loaded one dark for the one gain set instead of both gains. Ill try again tonight. Thanks. This does make it easier.
Darks, just looking into the code, this is only implemented for lights. I have to add a check for gain in darks creating and master dark selection. So this is not automated. You have to calibrate the lights separately with a different dark.
Adding gain for dark is not so difficult. I will do that the next days.
The code is ready. First something else and then I will upload for the Mac. Probably tomorrow.
Thanks. Han. Let me know if its up. I have about 3 images with more then one gain to stack :)
It is uploaded. You can try it :)