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Friday 5 December 2003 8.30am EST
| Last week the observing schedule was halted due to high radiation associated with solar flare activity. The loads were halted on Dec 2 at 12:31pm EST through an autonomous execution of the SI Safing SCS 107 and science was resumed at 9:27am EST on Dec 4. Six science observations (total 89.6 Ks) were impacted by the event and will be rescheduled in a later load.
The IEPHIN instrument has recently shown evidence of anomalous performance during periods of elevated operating temperature. In two cases the power supply voltage dropped as it became current limited due to the high temperature then returned to its nominal value once the unit cooled following a maneuver to a new attitude. The team has been monitoring a trend towards higher temperatures in this unit for some time and work is underway to develop an alternate radiation trigger using data from the HRC anticoincidence shield, in the event IEPHIN becomes unavailable. In the short term, observations will be scheduled to ensure that the unit does not reach temperatures high enough to cause anomalous performance. The observing schedule for the next week is shown below and includes an observation of GRS 1915+105 accepted as a Target of Opportunity on Dec 2. |
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Radiation Belts Dec 6 GRS 1915+105 (TOO) ACIS-S Dec 7 A267 ACIS-I ZCMA ACIS-S ACIS Background HRC-I Dec 8 0540-697 ACIS-S Radiation Belts Dec 9 IRAS FSC 09531+1430 ACIS-S Her X-1 ACIS-S/HETG SN 1986J ACIS-S Dec 10 Radiation Belts Dec 11 Epsilon ORI ACIS-S/HETG Dec 12 SC1329-313 ACIS-I Dec 13 MACS-J1226.8+2153 ACIS-I F1525-1892 ACIS-S GJ1245 ACIS-S Dec 14
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All spacecraft subsystems continued to support nominal operations.
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Revised: July 08, 2022