Optical System for the On-Orbit Calibration of the Wide Field/Planetary Camera

Abstract

In order to perform photometric measurements of astronomical objects with the Wide Field/Planetary Camera (WF/PC), the relative pixel-to-pixel response as a function of wavelength must be calibrated for each of the eight WF/PC CCDs. The current on-orbit camera does this by taking streak flats, which are obtained by pointing the entire Hubble Space Telescope at the Pacific Ocean. The operational costs in performing calibrations in this manner are considerable. Therefore, an in-flight calibration system is being added to the Wide Field/Planetary Camera II. This system will provide uniform illumination across each of the eight CCD detectors in the Camera for a wavelength range of 122 nm to 1100 nm.