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Saturation magnitude calculator

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#1 Lucullus

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Posted 16 March 2019 - 11:02 PM

Is there an online calculator that can estimate the saturation magnitude of a specific Imaging system, e.g. telescope, focal ratio, sensor QE, and exposure time? I can only find limiting magnitude calculators.

#2 freestar8n

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Posted 17 March 2019 - 12:08 AM

Is there an online calculator that can estimate the saturation magnitude of a specific Imaging system, e.g. telescope, focal ratio, sensor QE, and exposure time? I can only find limiting magnitude calculators.

It will depend critically on how big the star spots are in the image - and even what kind of profile they have.  If the fwhm is cut in half the peak pixel could go up by a factor of four or even more if it has a tighter overall shape.

 

You should be able to calculate the total count of electrons generated by a star of a given magnitude in a given time - but then you need to see how those electrons are spread across the pixels.  And that would be hard to do.

 

I would just look at stars in your own images with a given sensor and see if you can estimate how they would behave with a different system - if they are about the same size and shape.

 

And if you are imaging and you see stars saturating - which may or may not be ok depending on what you are doing - you can shorten exposure, change gain - etc.

 

Frank


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