During the last week, the observing schedule was interrupted for a Target of Opportunity observation of GRB250314A on Mar 23. The schedule was again interrupted due to a radiation monitor threshold violation consistent with bright source fluctuations exceeding trip parameters on ACIS. The loads were autonomously halted at 5:34 p.m. EDT on Mar 24 by the ACIS radiation monitor through execution of SCS 107 for SI safing. All spacecraft actions were nominal. A real-time procedure was executed on Mar 24 to disable SCS-29, which was enabled during the safing sequence. Planned observations that were impacted by the interruptions will be rescheduled.

A Chandra image release was issued on Mar 27 describing Chandra observations of the double star system GRO J1665-40, which consists of a stellar-mass black hole and a companion star. The more massive of the original star pair, with a shorter lifetime, exploded and expelled its outer layers into space, leaving a black hole; some of that expelled material was captured by the companion star and later accreted onto the black hole, creating a wind that could be detected and analyzed from Chandra data. The analysis showed that the original more massive star had about 25 times the mass of the sun and was much richer in heavy elements. For details see: https://chandra.harvard.edu/photo/2025/j1655/

The schedule of targets for the next week is shown below and includes observations of GRB250314A, which is a follow-up to a Target of Opportunity accepted on Mar 16, observations of Jupiter coordinated with Juno, and observations of M87 coordinated with Event Horizon Telescope and NuSTAR.