Friday 28 August 2009 10.00am EDT
|During the last week the observing plan was halted on August 28 due to
an incorrect load running on the spacecraft. The loads had been
replanned early in the week to allow time for a MUPS diagnostic
thruster firing but one load segment from the original schedule for
the week was mistakenly uplinked midweek. Ground procedures will be
modified to prevent this mistake from occurring in the future. In
conjunction with halting the on-board loads real-time procedures were
performed to prepare ACIS for entering the Earth's radiation belts and
to dump the memory locations of the suspect load segment. Observations
of SDSS J235833.20+0034 and IRAS 01298-0744 were affected by the
interruption and will be rescheduled in a future week.
A real-time procedure was conducted on August 26 to perform a diagnostic firing of the MUPS thrusters as part of the investigation of the anomalously low reading for the pressure in the MUPS tank. The impulse generated by the thrusters during the test reflected a tank pressure consistent with the pre-anomaly reading, indicating that the root cause for the anomalously low readings was faulty readings from the pressure transducer. Given this result, the attitude restrictions imposed to minimize the temperatures of the MUPS tank and fill panel have been lifted and the scheduling of momentum dumps to manage spacecraft angular momentum is once again allowed.
A Chandra image release was issued on August 27 of Cygnus X-1. The Cygnus X-1 system consists of a black hole with a mass about 10 times that of the Sun in a close orbit with a blue supergiant star with a mass of about 20 Suns. Gas flowing away from the supergiant in a fast stellar wind is focused by the black hole, and some of this gas forms a disk that spirals into the black hole. The gravitational energy release by this infalling gas powers the X-ray emission from Cygnus X-1. For further details see: http://chandra.harvard.edu/photo/2009/cygx1/
The schedule of targets for the next week is shown below
Radiation Belts Aug 30 SPT-CL2343-5411 ACIS-I Aug 31 ZwCl0348 ACIS-S Sep 1 NGC7814 ACIS-S Radiation Belts Sep 2 SPT-CL2343-5522 ACIS-I Sep 3 MRK996 ACIS-S SDSSJ204744.81-0618 ACIS-S Sep 4 SDSSJ205822.14-0650 ACIS-S PGC65766 ACIS-S SDSSJ210455.31-0035 ACIS-S IGRJ01400-0757 ACIS-I Sep 5 Radiation Belts SDSSJ212402.97+1147 ACIS-S IGRJ01517-0533 ACIS-I NGC788 ACIS-S Sep 6 ZwCl235 ACIS-S KUG0201-103 ACIS-S SPT-CL2356-5056 ACIS-I
All spacecraft subsystems continued to support nominal operations.
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