Instrument Science Report 2001-02:

Noiseless Preflashing of the WFPC2 CCDs

A.B. Schultz, I. Heyer, and J. Biretta

February 12, 2001

Abstract:

We present results from analysis of WFPC2 images obtained prior to and following pre-flashing the CCDs (WFPC2 CAL program ID: 8450). A crowded field in the globular cluster Omega Cen (HD116790) was observed, and the WFPC2 calibration lamp was used as the preflash source for the CCDs. A modest enhancement of ~3% in the detected counts was measured for point sources far from the horizontal shift register (at Y=800) for the preflash exposure. For the preflashed exposure, the second image after a preflash showed a decrease in the detected counts. The CCDs essentially returned to a previous sensitivity level.

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