Wide-Field Camera 3 ground testing and calibration

Wide Field Camera 3 (WFC3), a panchromatic imager being developed for the Hubble Space Telescope (HST), is now fully integrated and has undergone extensive ground testing at Goddard Space Flight Center, in both ambient and thermal-vacuum test environments. The thermal-vacuum testing marks the first time that both of the WFC3 UV/Visible and IR channels have been operated and characterized in flight-like conditions. The testing processes are completely automated, with WFC3 and the optical stimulus that is used to provide external targets and sources being commanded by coordinated computer scripts. All test data are captured and stored in the long-term Hubble Data Archive. A full suite of instrument calibration tests have been performed, including measurements of detector properties such as dark current, read noise, flat field response, gain, linearity, and persistence, as well as total system throughput, encircled energy, grism dispersions, IR thermal background, and image stability tests. Nearly all instrument characteristics have been shown to meet or exceed expectations and requirements. Solutions to all issues discovered during testing are in the process of being implemented and will be verified during future ground tests.