TITLE: GCN CIRCULAR NUMBER: 6760 SUBJECT: Swift observatory off line DATE: 07/08/13 22:11:09 GMT FROM: Neil Gehrels at GSFC N. Gehrels (NASA/GSFC) on behalf of the Swift Team Swift is currently not observing GRBs or other targets due to an attitude control problem that occurred Saturday morning (0726 UT Aug 11). A jump in gyro offset was observed on one of the units causing the spacecraft to go into sun reference pointing. A low power condition caused the instruments to be turned off. The spacecraft remains in sun reference and is stable with normal power and full batteries now. The gyro with the the offset jump is doubly redundant and we will switch to a redundant unit. The functionality and stability of the gyro with the offset jump will be tested for possible future use. Calibrating the new gyro combination and turning the instruments back on will take approximately 2 weeks. The BAT turn-on in particular takes more than a week. During this time the observatory will not be performing science operations. An announcement will sent out several days before science resumes.