Operations CXO Status Report

Friday 18 April 2003 8.30am EST

During the last week the observing schedule was interrupted following a high radiation event at 4:36pm on Apr 17 that stopped the daily load and activated the science instrument safing sequence (SCS 107). The event occurred just prior to radiation belt entry and is thought to be due to a 'puffed-up' belt state caused by high levels of coronal stream activity. The loads were replanned overnight and science will be re-started on radiation belt exit at 9am on Apr 18. 4Ks of the observation of RCS0439.6-2905 was impacted by the event. Following a period of noisy behavior during April 11-13 the IRU-1 gyro-1 current has settled to ~150mA (its yellow limit). Products to perform a swap to IRU-2 continue to be prepared in the event that they are needed. A Chandra press release was issued on 14 April that announced the detection of X-rays from a low mass brown dwarf in a multiple star system, which is as young as 12 million years old. For details see: http://chandra.harvard.edu/press/03_releases/press_041403.html. The observing schedule for next week is shown below and includes three observations of 3C58 totaling nearly 350Ks.

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Radiation Belts                     Apr 20
IGR J16358-4726        ACIS-S
PSR B1509-58           ACIS-I       Apr 21
UN J1141-0143          ACIS-S
OH231.8+4.2            ACIS-S
LNS 3                  ACIS-S       Apr 22
3C58                   ACIS-S
Radiation Belts                     Apr 23
3C58                   ACIS-S
Radiation Belts                     Apr 26
3C58                   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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