The performance and calibration of WFPC2 on the Huble Space Telescope

Abstract

The Wide Field Planetary Camera 2 (WFPC2) was installed in the HubbleSpace Telescope (HST) in 1993 December. Since then, the instrument hasbeen providing high-quality images. A significant among of calibrationdata has been collected to aid in the understanding of the on-orbitperformance of the instrument. Generally, the behavior of the camera issimilar to its performance during the system-level thermal vacuum testat JPL in 1993 May. Surprises were a significantcharge-transfer-efficiency (CTE) problem and a significant growth ratein hot pixels at the original operating temperature of the CCDs (-76 degC). The operating temperature of the WFPC2 CCDs was changed to -88 deg Con 1994 April 23, and significant improvements in CTE and hot pixels areseen at this temperature. In this paper we describe the on-orbitperformance of the WFPC2. We discuss the optical and thermal history,the instrument throughput and stability, the Point Spread Function(PSF), the effects of undersampling on photometry, the properties ofcosmic rays observed on-orbit, and the geometric distortion in thecamera. We present the best techniques for the reduction of WFPC2 data,and describe the construction of calibration products includingsuperbiases, super-darks, and flat fields.