ALFOSC CCD monitoring script documentation
To really understand how analysing script works, one should look at the script which take images, and script itself. Here is given only the ideas how different things are calculated.
Analysing is done using python scripts.
Preparation procedures
- 101x101 pixels sized image centered in the middle of the CCD is used, because that is the largest possible area uniformly illuminated by the betalight.
Good to know
- For general statistics the whole image area is used
- For real calculations images are divided into 16x16 pixel subimages
GAIN and RON calculations
- GAIN and RON are calculated using the 36 subwindows from flats and bias frames using Janesick's method
- In the end, sigma clipped mean of all results has been taken to be the GAIN and the standard deviation divided by square root of number of remaining subwindows of that clipped mean is taken as the error of the GAIN.
- For RON the sigma clipped gain value is used.
Count level
- Count level is measured taking first MEAN values from those 36 small boxes from both flats
- Then sigma clipped mean value is taken
- Errors are calculated dividing sigma clipped standard deviation by square root of number of used areas
BIAS level
- Bias level is measured taking first MEAN values from those 36 small boxes from both bias images
- Then sigma clipped mean value is taken
- Errors are calculated dividing sigma clipped standard deviation by square root of number of used areas
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