[vsnet-grb-info 5051] Swift observatory off line

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6760
SUBJECT: Swift observatory off line
DATE:    07/08/13 22:11:09 GMT
FROM:    Neil Gehrels at GSFC  <gehrels at milkyway.gsfc.nasa.gov>

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.