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Operations CXO Status Report
Friday 9/28/01 12.00pm EDT
During last week the observing schedule was interrupted
after the Observatory entered a bright star hold at 7.48am on Sept
22. The entry followed a 2.5 hour observation of the dark moon performed
on gyro-hold. Analysis of the dump data indicates that a gyro bias
error of ~170 arcsec accumulated during the gyro hold and subsequent
maneuver. The error exceeded the size of the aspect camera search
box during the next star acquisition and resulted in the bright star
hold. Data indicates that the gyro performance remains consistent
with past performance, however a detailed analysis will be performed
by the gyro vendor. Fine attitude was recovered at 11pm EDT on Sept
22, and loads were uplinked at 2pm on Sept 23. The observations of
Comet 19P/Borrelly, Puppis N Knot and 1RXS J1708-4009 were impacted
by the bright star hold.
The loads were interrupted a second time at 10.29am
on Sept 24 by a significant solar radiation event that stopped the
daily load and activated the science instrument safing sequence (SCS
107). All actions were nominal and assessment of the dump data confirmed
that the trigger was due to high proton counts in the EPHIN E1300
channel exceeding the pre-defined threshold of 10 counts/cm^2/s/sr.
The solar levels have remained high throughout the week but are projected
to reach an acceptable level during Sept 29. The loads are planned
to resume at 12.50am on Sept 30. The 10 observing targets impacted
by the radiation event will be rescheduled in a future load.
The schedule for next week is shown below.
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SGR 1627-41 ACIS-S Sep 30
IRAS 23128-5919 ACIS-S
Puppis A shock front ACIS-S Oct 1
Radiation Belts
CAL 83 HRC-S/LETG Oct 2
UV CETI,GLIESE 65 HRC-S/LETG
IRAS 05189-2524 ACIS-S Oct 3
Puppis bright E knot ACIS-S
Radiation Belts Oct 4
ABELL 496 ACIS-S
M31 Nucleus ACIS-S
M31 Nucleus ACIS-I Oct 5
A2556 ACIS-S
SAX J1753.5-2349 ACIS-S
XTE1650-500 ACIS-S/HETG
NGC6093 ACIS-S Oct 6
Radiation Belts
RCW103 ACIS-S Oct 7
PKS 2135-14 ACIS-S
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All spacecraft subsystems continued to operate nominally.
Return to 2001 Status Reports
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