WFC3 Instrument Science Report 2008-38 WFC3 TV3 Testing: IR Science Monitor H. Bushouse February 20, 2009 ABSTRACT Eight runs of the IR science monitor program were executed during WFC3 Thermal- Vacuum test #3, which provides a performance monitor of the IR channel via dark, flat field, PSF, and throughput test exposures. The results show very good repeatability and stability of all measured performance parameters and the IR channel easily meets or exceeds all of the Contract End Item requirements that can be assessed with these data. Introduction During Wide Field Camera 3 (WFC3) system-level thermal-vacuum testing campaign #3 (TV3), which took place at Goddard Space Flight Center from February to April 2008, the IR Science Monitor test was executed periodically in order to assess and monitor the overall performance of the camera over the 2-month duration of TV3. The science monitor includes darks, internal and external flat fields at different wavelengths, observations of calibrated sources for measuring instrument throughput, and observations of unresolved sources to monitor imaging quality. These data allow us to measure and track the stability and repeatability of fundamental parameters of the IR-4 flight detector and the WFC3 instrument, such as dark current, read noise, dead and hot/cold pixels, optical throughput, and PSF stability. The IR science monitor was executed a total of eight times during TV3, using WFC3 ground test Science Mission Specification (SMS) IR19S01. The IR-4 detector was at a flight-like temperature of -128° C for all runs. Four of the runs were performed during Operated by the Association of Universities for Research in Astronomy, Inc., for the National Aeronautics and Space Administration 1