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EP35 - YouTube - The HOYS Citizen Science Project by Dr Dirk Froebrich


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This is super interesting and something I'd definitely like to participate in. I have just one possibly silly question... as Dirk said the image to be submitted need to be calibrated and preferably stacked, but nothing was mentioned about stretching. I'm assuming as it is photometry that stretching in any form would be destructive to the data? Or would a linear stretch be acceptable? 

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On 08/02/2021 at 05:58, CraigT82 said:

This is super interesting and something I'd definitely like to participate in. I have just one possibly silly question... as Dirk said the image to be submitted need to be calibrated and preferably stacked, but nothing was mentioned about stretching. I'm assuming as it is photometry that stretching in any form would be destructive to the data? Or would a linear stretch be acceptable? 

Hi Craig, I didn't know the answer to to your question as I haven't got an imaging rig up and running yet so haven't contributed my own data, but I asked Dirk and this was his reply:

"calibration means dark/bias and flatfield correction.

Then we want those, reduced, fits files. under no circumstances should anything else been done to the images before submitting (do whatever you like with the images afterwards though 😉 Any stretching destroys the ability to calibrate the photometry - this is all we are interested in!"

 

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Yes @markse68 is right. Just calibrated but stop before you start doing the stuff we astro-imagers like to do to make the images pretty :)

I try and automate as much of the workflow as possible to make it easier and more consistent. I wrote an article about it on the HOYS website here:

https://hoys.space/a-hoys-participant-perspective-4/

Basically use a script in SiriL that does all the processing if you put your data - lights, flats, bias, darks - in the right directories. 20s later the stacked and calibrated files pop out at the end. Hope it's useful.

Mark (P)

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3 minutes ago, CraigT82 said:

Thanks Mark and Mark!

Yes I thought as much. 

What does the term 'reduced' mean with reference to the FITS files? 

I think he means calibrated (darks, flats corrected)

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2 minutes ago, CraigT82 said:

Thanks Mark and Mark!

Yes I thought as much. 

What does the term 'reduced' mean with reference to the FITS files? 

I think it's  just another way of saying "processed". Literally all I do is take 3x180s images for each filter of an object (that exposure works for me), calibrate them with flats, darks, bias, stack the 3 images and that's it. I also update a couple of items in the FITS header that helps processing (FILTER and EXPTIME if it's not there - DATE-OBS should already be set). Upload to the HOYS server and go through a short amount of processing there.

M

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