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#1 GeorgeCarey

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Posted 13 August 2019 - 10:19 AM

Are there any experts on FITS images out there?

 

I have a friend who is a whizz at programming and have coaxed him into developing software that can take a few FITS images and search for new objects.

In other words, automated nova/supernova detection.

 

He has had some success in reading a FITS image, despite the incomprehensible information about the data structure.

 

For some strange reason, we are getting the right hand 280 columns appearing at the left - despite reading the data sequentially from the start.

 

The image is 3326 x 2504 pixels.

 

Very stretched image below:

 

Any help would be much appreciated!

Attached Files


ASA DDM60Pro, homemade 8" and 10" reflectors, QSI 683 camera, Astrodon 5nm filters, Pulsar dome observatory. Website: http://www.geoastro.co.uk


#2 GeorgeCarey

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Posted 14 August 2019 - 09:08 AM

Great progress. We are now able to extract adu values from the fits file that agree with Maxim.

The hardest part is done!

 

bingo!.jpg


ASA DDM60Pro, homemade 8" and 10" reflectors, QSI 683 camera, Astrodon 5nm filters, Pulsar dome observatory. Website: http://www.geoastro.co.uk


#3 LaCebra

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Posted 22 August 2019 - 03:51 AM

Hi George,

 

Several years ago, I processed "fits" images in an elementary way (autostrech).
For that I used a library of functions in C#, NASA origin (?)
There was indeed a "bug" in their source code. After correction everything worked well.

If necessary, I could look for these elements.

Good luck with that.
La Cebra


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#4 Waldemar

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Posted 22 August 2019 - 08:03 AM

Hi George,

 

Several years ago, I processed "fits" images in an elementary way (autostrech).
For that I used a library of functions in C#, NASA origin (?)
There was indeed a "bug" in their source code. After correction everything worked well.

If necessary, I could look for these elements.

Good luck with that.
La Cebra

 

Hi La Cebra,

 

You mean the 'Fits Liberator' programm from the NASA?
Can I ask what you corrected in their source code?

 

Best regards,

Waldemar


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#5 GeorgeCarey

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Posted 22 August 2019 - 08:24 AM

Thanks  La Cebra,

My friend programs in Delphi and it looks like there are no FITS libraries available.

He is having fun working it all out from scratch!


ASA DDM60Pro, homemade 8" and 10" reflectors, QSI 683 camera, Astrodon 5nm filters, Pulsar dome observatory. Website: http://www.geoastro.co.uk


#6 LaCebra

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Posted 22 August 2019 - 03:14 PM

@George 

 

You can see that...

 

https://fits.gsfc.na...s.html#delafits
 

 

DeLaFits

DeLaFits (free software, MIT License) is published on GitHub. DeLaFits is native for Delphi and Lazarus and is not a wrapper around another library.
Features: building, reading, editing, and rendering of a FITS primary array image.
DeLaFits supports only Single Image (one header and one data unit).

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#7 LaCebra

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Posted 22 August 2019 - 03:17 PM

@Waldemar

 

No, it's CSharpFITS - a complete C# library to FITS (but with a little bug :wacko: )

 

 


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#8 GeorgeCarey

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Posted 23 August 2019 - 09:36 AM

LaCebra - that looks very interesting! I will pass that along to Lutgen. (the programmer).

 

We have a small problem reading FITS from another friend of mine.

In his header there is a keyword 'BIAS' which does not seem normal. It is not to do with bias calibration frames.

It does not seem to be a standard keyword?

In his reference image he has BZERO=33753.0 and in other images it is the usual 32768.0  (2^15)

Also his reference image has BSCALE=0.9699392681661427    and in others it is the usual 1.0000

Very odd.


ASA DDM60Pro, homemade 8" and 10" reflectors, QSI 683 camera, Astrodon 5nm filters, Pulsar dome observatory. Website: http://www.geoastro.co.uk


#9 LaCebra

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Posted 23 August 2019 - 10:52 AM

Hello George,
 
1 - I have a definite advantage with C# - CSharpFITS
I was able to extract the functions I needed, then decode line by line what needed to be done.
And then I copied/reprogrammed as needed (store my Bias, Darks, Flats, Lights images in SQL-Server).
I mean, I forgot everything  :D 
 
It is frankly more difficult in Delphi where sources are scarcer.
 
 
2 - Can you publish one of these images in the cloud, describe the shooting (software, camera, etc.), and finally make a synthesis of your current analyses.
I'm not sure I have an immediate answer, however....
 
 
3 - Astronomical photography is of the same nature as Lucky Luke : A long and lonely journey :)
 
 
La Cebra
 
(Translated with www.DeepL.com/Translator)

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#10 GeorgeCarey

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Posted Yesterday, 08:27 AM

Good progress made. I decided to hack into the FITS files myself - the hard way!

I have no way of reading Hex values from a file so found a hex reader on the web, and a hex to decimal converter.

I can now read the 16 bit FITS files and get exactly the same adu values out as Maxim does.

I then wrote a spreadsheet that would do the task - success.

Lutgen found a bug in his code late last night - an overflow was occurring, so I think we are back on track.

 

!Bingo.jpg


Edited by GeorgeCarey, Yesterday, 08:30 AM.

ASA DDM60Pro, homemade 8" and 10" reflectors, QSI 683 camera, Astrodon 5nm filters, Pulsar dome observatory. Website: http://www.geoastro.co.uk


#11 GeorgeCarey

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Posted Yesterday, 08:29 AM

And the spreadsheet - dealing with the peculiar values of BZERO and BSCALE:

 

RonsReferenceImage.jpg


ASA DDM60Pro, homemade 8" and 10" reflectors, QSI 683 camera, Astrodon 5nm filters, Pulsar dome observatory. Website: http://www.geoastro.co.uk





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