A CCD ANTI-BLOOMING TECHNIQUE FOR USE IN PHOTOMETRY

A new anti-blooming technique was used to collect images for a BL Lac monitoring project. The anti-blooming was accomplished by clocking two of the collection phases (in a three phase chip) back and forth during the integration of an image. Calibrations were done using VRI standard stars to insure that the technique did not affect normal photon collection and photometric data. New sources of noise were identified which must be subtracted from the processed image. In contrast, the technique reduced dark current noise, which is of benefit with a thermo-electric-cooled camera. The technique eliminated blooming across the stars of interest, while preserving photon-collection efficiency. It also reduced the total noise of the exposures.