AAVSO: American Association of Variable Star Observers

Measuring and Correcting Non-linearities in ABG Cameras (Abstract)

Volume 47 number 2 (2019)

Richard Wagner
126 Powell Bay Road, Elgin, ON K0G 1E0, Canada

Abstract

(Abstract only) Most of the commercially available astronomical CCD cameras for the amateur astronomer incorporate an anti-blooming gate (ABG). It is widely accepted that the ABG introduces significant non-linearities and as a result these cameras are not recommended for astronomical photometry. Having two of these cameras, the SBIG ST2000XM and the QSI583ws, I investigated their non-linearities with a view to determining just how large the problem is and how it could be corrected. In response tests to a constant light source both cameras show a linearly decreasing flux (ADU/s) as a function of increasing signal. A quadratic function is fitted which corrects the non-linearities to a remaining non-linearity of < 8ADU RMS from 0 to 55000ADU signal.