Calibration frames

No clear sky so this night has been devoted to calibration frames acquisition for all my 2x2 bin images. Standard calibration requires bias, dark and flat reference image to clean up an image from noise and optical/geometrical artifacts.

A lot of bias (74 of them...) median stacked give this master bias frame:

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Master dark frame (median of 60 frames, -15 C, 60 seconds each...):

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Master flat frame (median of 90 frames) obtained using a 14" elettroluminescent flat panel:

(click to enlarge)

Some dust donuts.....smaller donuts are from the sensor window protection glass, larger ones are from the filters in the filter wheel.

Using those master frames should keep my images cleaner....I hope so!!!...