Applying dark results in dark image

Image processing, astrometry, photometry, etc.
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Rudi
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Joined: 08 Jan 2019, 04:47

Applying dark results in dark image

Post by Rudi » 30 Nov 2019, 06:42

I have a master dark, based on 50 x 300 sec darks:
https://www.dropbox.com/s/ep1d73p3owni0 ... s.fit?dl=0

The master dark is made by stacking "Sigma + Sum" the 50 individual darks and then saving the result as a fits file.

If I use this master dark the result in Preprocessing is a almost completely black image with no data:
One of the lights: https://www.dropbox.com/s/c1peg57hwapxb ... 7.fit?dl=0

Try preprocessing then above light, using the above dark.

I am using AstroArt 7 + SP2.

Am I creating the master dark in a wrong way? Do I need to align the bit depth of the dark and light (and how do I do that)?
/Rudi

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Rudi
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Joined: 08 Jan 2019, 04:47

Re: Applying dark results in dark image

Post by Rudi » 30 Nov 2019, 07:13

Hi again - sorry for the inconvenience, I think I found out my self.
I had a look in the AA7 help, there's a section called "Calibration".
From what I understand, AstroArt will generate the three master calibration images by following the instructions given here.
I will try that out.

Image
/Rudi

fabdev
Posts: 134
Joined: 03 Dec 2018, 21:43

Re: Applying dark results in dark image

Post by fabdev » 30 Nov 2019, 12:26

Hi, master darks cannot be done with "Sum" methods, it's required to use the "Average" methods, otherwise they will have a diffent scale compared to light images.
With that dark frame you can solve dividing the image by 50 then saving it.

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Rudi
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Re: Applying dark results in dark image

Post by Rudi » 23 Jan 2020, 10:16

Hi again Fabio,

One question, is it possible to create just a master flat with just the flats? Or do AA need darkflats and darks for the process.
Does the three goups have any influence on each other? Can I make master flat only, and then flat darks only and then dark only?

I have 100 x dark, 25 x L_flat, 25 x R_flat, 25 x G_flat, 25 x B_flat, 25 x Halpha_flat, 25 x Oiii_flat, 25 x VJohnson_flat, 25 x no-filter_flat and also 25 x darkflat for each of the exposure times used for flats

Do I have to include all darks for every run:

Run 1):
Flat Fields: 25 x L_flat
F.Dark Frames: 25 x dark_with_same_exposuretime_as_flat
Dark Framed: 100 x dark

Generates a MasterDark, Master_L_Flat and Master_FlatDark_Xseconds

Do I need all the darks for the next run? Or can I leave the dark frames list empty or use the master dark?
My guess, is that no darks are needed at all, in order to create master flat and master flat dark, since master dark is only used for the light frames.
/Rudi

fabdev
Posts: 134
Joined: 03 Dec 2018, 21:43

Re: Applying dark results in dark image

Post by fabdev » 23 Jan 2020, 14:49

Hi Rudi, for maximum productivity, you should prepare and Save some empty preprocessing with your flats and darks, so that you can recall them with one click.

Yes, any combination of master flats and dark is possible: a list of N# flats in a box can be replaced by a single flat which was averaged previously. But if you prepare and save the Preprocessing this is not needed, the files will be averaged very quickly at runtime.

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Rudi
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Joined: 08 Jan 2019, 04:47

Re: Applying dark results in dark image

Post by Rudi » 23 Jan 2020, 15:26

Thanks Fabio - and Yes, I will try making a script for the job.
I will share it here.

Another thing in the same area; will it be possible to make the sequence window wider?
It is hard to see the exposuretimes if in milliseconds.
/Rudi

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Rudi
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Joined: 08 Jan 2019, 04:47

Re: Applying dark results in dark image

Post by Rudi » 23 Jan 2020, 15:54

I imagine something like this would do, but how do I save the result in the function createFlats?

Code: Select all

# Create flats

#function createFlats(flatType)
  rootDir = "C:\1 - ZWO Images\flat\"
  pre = "#PREPROCESSING" + CRLF
  flats = FindFiles(rootDir, "flat*" + flatType + ".fit")
  n = Count(flats)
  for i = 1 to n
    pre = pre + "Flat = " rootDir + " + im(i) + CRLF
  Next i
  pre = pre + "AlignMethod=1" + CRLF
  Preprocessing(pre)
end function

createFlats("L")
createFlats("R")
createFlats("G")
createFlats("B")
createFlats("H-alpha")
createFlats("O-III")
createFlats("V-JOH")
createFlats("V-MTY")
/Rudi

fabdev
Posts: 134
Joined: 03 Dec 2018, 21:43

Re: Applying dark results in dark image

Post by fabdev » 23 Jan 2020, 22:04

I meant the "Save" and "Open" buttons of Preprocessing, not scripts. Just save some Preprocessing with zero images but with the flat and darks that you need. Maybe I didn't understand the question.

With a script you could also save the "pre" variables as text, then in Preprocessing you could open and use it, instead of using the script Preprocessing(pre) function. If instead the script is used to create master flat fields, then it's OK, just save or rename each image, and remove the "#".
I will take a look at the sequence window soon.

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