2.1 STIS Repair and Return to Operations

In May 2001, the Space Telescope Imaging Spectrograph (STIS) switched over from using Side-1 to Side-2 electronics when a short circuit blew a fuse, knocking out the Side-1 electronics. STIS operated on Side-2 electronics until it ceased science operations on 03 August 2004, due to the failure of a power supply within the Side-2 electronics.

In May 2009, during the fourth spacewalk of the HST Servicing Mission 4, (SM4), the STIS Side-2 circuit board containing the failed low-voltage power supply was replaced. This repair fully restored the STIS instrument to operation with capabilities similar to those it had before the Side-2 failure. In the appropriate sections of this Handbook, the performance changes since 2004 in detector dark currents, throughputs, and charge transfer efficiency (CTE) will be discussed.

Many figures and tables were originally updated for the Cycle 17 (first post-SM4) version of this handbook, using our best estimates of instrument performance for Cycle 17. In many cases, those figures and tables have not been revised to take into account the modest changes expected between those projected values and the estimated Cycle 32 performance. For more up-to-date performance values, users should consult the Performance section of the STIS web pages and the STIS ETCs.

The sensitivities and other instrument parameters adopted for use with the Cycle 32 ETCs have been updated with our best estimates for April 2025.

STIS will be among the instruments available for inclusion in Cycle 32 Phase I proposals. Please consult the Cycle 32 Call for Proposals and the Cycle 32 Proposal Announcement webpages (available through the Proposing Overview web page) for any updates on instrument status.