During the last week Chandra's observing schedule was interrupted by a spacecraft Safe Mode event that occurred at 12:11pm EST on Mar 3 and was detected at the start of a scheduled contact at 2:45pm EST. The Safe Mode transition was nominal and all systems functioned as expected. The cause of the Safe Mode was a trip of the sun-position monitor; the trip occurred near the end of a maneuver to a scheduled attitude that had an off-nominal roll that was very near the position-monitor limit. Analysis of SSR playback data confirmed that a small FSS alignment calibration error caused the on-board estimate of the sun position to be slightly outside the allowable region, leading to the trip of the Sun-Position Monitor. No hardware issues have been identified as contributing to Safe Mode entry. The Chandra Operations team completed the Safe Mode recovery procedure to the prime hardware at 9:40pm EST on Mar 3 and clean-up activities to prepare for a transition to attitude control by pointing at stars later today.

A real-time procedure was executed on Mar 1 to perform a routine self-check of the Electrical Interface Assembly (EIA) Sequencer.

Of note this week was the release on Feb 29 of CIAO 4.8.2, containing a bug fix that only affects the OS X 10.11 (El Capitan) pre-compiled binaries.