Status of the STIS Instrument After Repair During Sm4

The Space Telescope Imaging Spectrograph (STIS) was installed in the Hubble Space Telescope (HST) in February of 1997, and operated until August of 2004, when an electrical malfunction in a power supply forced cessation of operations. On May 17,2009, during the fourth EVA of SM4, astronauts Michael Good and Mike Massimino undertook an eight-hour spacewalk, during which they replaced the STIS LVPS-2 circuit board containing the failed component, successfully repairing STIS. We will review the scientific capabilities and operational status of STIS after this repair. In most respects, STIS after the 2009 repair operates in much the same way as it did prior to the 2004 failure. Most changes in performance are close to what had been expected. The degradation of the STIS CCD due to radiation damage and the modest changes in optical throughput are consistent with extrapolation of previously-observed trends. Internal and external alignments of the instrument are also similar to what they were in 2004. The biggest surprise is that the dark current for the NUV MAMA detector is several times larger than had been expected and is only slowly decreasing towards its expected range. We discuss how these changes will affect science with STIS now and in the future.