New public domain software: astro-dark-frame-library-manager

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oopfan
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New public domain software: astro-dark-frame-library-manager

Post by oopfan » Fri Sep 14, 2018 2:45 pm

Hi everyone,

I just released software to GitHub to help manage Dark frames and Light frames by temperature. It all began with this forum post last week:

viewtopic.php?f=16&t=1090

I hope you find it useful. I wrote extensively about the How's and Why's in the documentation but I still need to fill in the information about the Arduino temperature logger that I use.

You can find the GitHub repository here.

Brian

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Re: New public domain software: astro-dark-frame-library-manager

Post by mAnKiNd » Fri Sep 14, 2018 4:08 pm

Nice work Brian, could be very useful for owners of uncooled cameras.

Cheers
Minos
Celestron AVX & SW Az-GTi (EQ)
SW Esprit 80 & 150PL, Canon 300mm f4 (non-IS)
ASI1600MM PRO
EFWmini - HOLRGB
ASI120MM mini for guiding
SC CDC PHD2 DSS PI PS

https://www.astrobin.com/users/minoSpace/

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Re: New public domain software: astro-dark-frame-library-manager

Post by oopfan » Fri Sep 14, 2018 4:59 pm

Thanks, Minos! It's funny how 144 lines of code can lead to 192 lines of documentation.

Brian

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Re: New public domain software: astro-dark-frame-library-manager

Post by turfpit » Fri Sep 14, 2018 6:38 pm

Nice piece of work Brian and my compliments on the documentation.

Dave

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Re: New public domain software: astro-dark-frame-library-manager

Post by oopfan » Fri Sep 14, 2018 7:41 pm

Thanks, Dave! Actually it's not hard when it is something you love.

Brian

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Re: New public domain software: astro-dark-frame-library-manager

Post by oopfan » Sat Sep 15, 2018 4:39 pm

Last night I collected darks from 9pm to 6am.

I am preparing a darks library for SHO. I took an educated guess based on previous experience with Hydrogen Alpha that an exposure of 50 seconds, unity gain of 389, and offset of 30 is ideal. Well, maybe not "ideal" but I will get a stackable print without saturating stars.

Here is the breakdown by temperature:
  • 60.0F: 19 frames
    60.5F: 53 frames
    61.0F: 10 frames
    61.5F: 94 frames
    62.0F: 47 frames
    62.5F: 159 frames
    63.0F: 75 frames
    63.5F: 28 frames
    64.0F: 51 frames
    64.5F: 39 frames
    65.0F: 9 frames
    65.5F: 28 frames
To illustrate how much darks change with temperature, here are statistics from FITS Liberator:
  • At 65.5F: Mean: 676, Standard Deviation: 152
    At 60.0F: Mean: 628, Standard Deviation: 125
I certainly have more work to do. Ideally, I'd like each temperature bucket to have 100+ frames, and of course I need a wider temperature range as we move into cooler temperatures this time of year.

It sure will be nice to just concentrate on lights from now on.

Brian

PS: I discovered a typo in the docs, and a bug in the software. All fixed now.

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Re: New public domain software: astro-dark-frame-library-manager

Post by oopfan » Sun Sep 16, 2018 11:48 am

Captured another 10 hours of darks last night.

Here is the updated breakdown by temperature:
  • 60.0F: 28 frames
    60.5F: 64 frames
    61.0F: 61 frames
    61.5F: 231 frames
    62.0F: 108 frames
    62.5F: 202 frames
    63.0F: 125 frames
    63.5F: 76 frames
    64.0F: 92 frames
    64.5F: 79 frames
    65.0F: 27 frames
    65.5F: 44 frames
    66.0F: 62 frames
    66.5F: 21 frames
    67.0F: 28 frames
    67.5F: 23 frames
    68.0F: 29 frames
    68.5F: 20 frames
    69.0F: 14 frames
Also, here is a graph of temperature vs time from last night. Time UTC, Temp is Fahrenheit.

Brian
Attachments
Temp vs Time.jpg
Temp vs Time.jpg (54.08 KiB) Viewed 249 times

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Re: New public domain software: astro-dark-frame-library-manager

Post by turfpit » Sun Sep 16, 2018 1:53 pm

Very interesting Brian - a 7deg C drop.

A demonstration of what happens when 9am darks are applied to 9pm lights and vice versa would be very educational. An extreme test but should be a good demonstration about why to avoid temperature mismatches.

Dave

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Re: New public domain software: astro-dark-frame-library-manager

Post by mAnKiNd » Sun Sep 16, 2018 3:26 pm

This is indeed really very interesting. I just wanted to share a different thought to add here, not in anyway trying to take away from your approach though.

I can't help but thinking that when I faced this issue with mismatched temperatures in dark subtraction with my DSLR, I always adopted the LENR function to automatically take a single dark to be subtracted from the preceding light, this of course at the expense of half my skytime, but it worked surpisingly well (there are of course arguments for master dark subtraction beeing better than single dark frame subtraction).

When I use to do this, it was an effort to avoid the problem you illustrate above as much as possible. I think this could be another way to be able to apply such an approach to uncooled CMOS cameras, for the camera to either have a mechanical shutter, which it obviousky doesn't and probably never will, or connected to a filter wheel with a dark frame filter. Of course, you'd need still need a script or some function that doesn't exist yet, which would mimick the function carried out by DSLR LENR - take a light then immediately after a dark frame, then subtract it from the light and render a single dark subtracted single light frame to work with.

Just a thought
Minos
Celestron AVX & SW Az-GTi (EQ)
SW Esprit 80 & 150PL, Canon 300mm f4 (non-IS)
ASI1600MM PRO
EFWmini - HOLRGB
ASI120MM mini for guiding
SC CDC PHD2 DSS PI PS

https://www.astrobin.com/users/minoSpace/

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Re: New public domain software: astro-dark-frame-library-manager

Post by oopfan » Sun Sep 16, 2018 4:34 pm

Dave,

That is a good idea. I should purposely stack NGC 7635 with mismatched temperature lights and darks to show how the image quality deteriorates!

Thanks,
Brian

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