Friday 26 August 2016 9.00am EDT
During the last week the Chandra observing schedule was interrupted by an entry to Bright-Star Hold mode (BSH) at 3:24am on Sunday, Aug 21 due to the failure to acquire the commanded stars in the aspect camera at the end of a maneuver. The entry into BSH was nominal and an assessment of the telemetry indicated that all spacecraft hardware was performing nominally. The most-likely cause for failing to acquire stars is that a gyro-bias excursion occurred during the maneuver, which resulted in a maneuver error that placed the commanded acquisition stars outside of their search boxes. An analysis of star data during BSH transition indicated that the error was ~126 arcsec, which is consistent with previously seen gyro bias excursions. Real-time procedures were executed on Aug 21 to recover from BSH. Loads for a replanned schedule were uplinked on Aug 22 with 75.9ks of science loss. Observations of CODEX 25953, M81 N, and fcc47 were impacted by the interruption and will be rescheduled. A real-time procedure was executed on Aug 25 to uplink a flight software patch that increases the HRMA average maximum temperature thermal health-check threshold. This update is in response to increasing temperatures due to degradation of the Observatory's thermal covers during the mission and will reduce the possibility of an unnecessary swap to redundant thermal control hardware due to environmental heating. The schedule of targets for the next week is shown below and includes an observation of M82 offset 1 coordinated with NuSTAR and on observation of 2MASS J06022918+4951561 coordinated with ground-based observatories. |
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Radiation Belts Aug 29 PSZ2G127.01+26.21 ACIS-I 2MASSJ06022918+4951 ACIS-S fcc63 ACIS-S SPT-CLJ2331-5051 ACIS-I RXJ0852.0-4622 ACIS-S Aug 30 Radiation Belts Aug 31 CygnusA-EHotspot ACIS-I Abell1795outskirts ACIS-I Sep 1 PSZ2G066.41+27.03 ACIS-I Sep 2 PSZ2G295.25-21.55 ACIS-I SPT-CLJ2331-5051 ACIS-I Radiation Belts Sep 3 M82offset1 ACIS-I GRB160625B ACIS-S CSWA14 ACIS-S 2MASXJ03502377-50183 ACIS-S Sep 4 PSRJ2124-3358 ACIS-S fcc153 ACIS-S Sep 5 Radiation Belts
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All spacecraft subsystems continued to support nominal operations.
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