GCN Circular 9922
Scott Barthelmy and Neil Gehrels, on behalf of the Swift Team: The Swift-BAT instrument experienced a partial flight software crash around ~10:30 UT on 17 Sep 2009. All the temperatures, voltages, currents, etc indicate that the instrument is fine -- only the science collection portion of the flight software has stopped working. The fundamental problem has been identified and a fix to the software is being implemented. The portion that runs the observing program continues to run, so the spacecraft continues to point and collect NFI data on the planned targets. It will take several days to get the BAT flight software running again; and during that time there will be no BAT triggers on new GRBs.