Operations CXO Status Report

Friday 25 July 2003 9.30am EDT

During the last week the observing schedule was replanned to include an observation of the the X-ray Flash source H2777 that was accepted as a 3 day turn-around Target Of Opportunity (TOO) on 23 July. Loads were replanned and uplinked on Jul 24 for the observation on Jul 25. A portion of an observation of M8 was impacted by the TOO and has been rescheduled for next week. As previously reported, the swap from Inertial Reference Unit-1 (IRU-1) to IRU-2 was completed as planned on July 19 and the mission is proceeding nominally under IRU-2 control. IRU-1 is now configured as the backup IRU for use in the event of a safemode transition. A set of maneuvers was performed following the swap to verify the updated IRU calibration and completed with acceptable results. The swap was performed during a perigee passage and the science program was restarted following radiation belt exit. A real-time procedure was completed on July 22 to perform a manual unload of momentum. The unload was performed at an attitude that ensured a cooler starting temperature than prior anomalous unloads. Thruster performance was nominal during the unload. The observing schedule for next week is shown below.

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Radiation Belts                     Jul 27
M8                     ACIS-I
ZWCL1215               ACIS-I       Jul 28
J1314+3649             ACIS-S
NGC5678                ACIS-S
PC 1447+4750           ACIS-S
HR 6406                HRC-I
V404 CYG               ACIS-S
NGC7465                ACIS-S       Jul 29
3810                   ACIS-S
M33 X-8 (Nucleus)      HRC-S
Radiation Belts
H1743-322              ACIS-S/HETG  Jul 30
A3571                  ACIS-S       Jul 31
NGC 4168               ACIS-S
EXO 1747-214           ACIS-S
OGLE-1999-BUL-32       ACIS-S
G11.2-0.3              ACIS-S       Aug 1
AX J1845-0258          ACIS-S
Radiation Belts
SDSS J0654.11-001533.4 ACIS-S       Aug 2
MS0440.5+0204          ACIS-S
NGC 988                ACIS-S
A209                   ACIS-I       Aug 3
F01004-2237            ACIS-S
SGR 1806-20            ACIS-S

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All spacecraft subsystems, with the exception of the MUPS thruster A-1 under investigation, continued to operate nominally.

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