The performance and calibration of WFPC2 on the Huble Space Telescope

Abstract

The WFPC2 was installed in the Hubble Space Telesocpe (HST) in December 1993. Since then, the instrument has been providing high quality images. A significant amount of calibration data has been collected to aid in the understanding of the on-orbit performance of the instrument. Generally, the behavior of the camera is similar to its performance during the system-level thermal vacuum test at JPL in May 1993. Surprises were a significant charge transfer efficiency (CTE) problem and a significant growth rate in hot pixels at the original operating temperature of the CCDs (-76 C). The operating temperature of the WFPC2 CCDs was changed to -88 C on 23 April 1994, and significant improvements in CTE and hot pixels are seen at this temperature. In this paper we describe the on-orbit performance of the WFPC2. We discuss the optical and thermal history, the instrument throughput and stability, the PSF, the effects of undersampling on photometry, and properties of cosmic rays observed on-orbit, and the geometric distortion in the camera. We present the best techniques for the reduction of WFPC2 data, and describe the construction of calibration products including superbiases, superdarks, and flat fields.