During the last week Chandra completed the observing schedule as planned.

Chandra press and image releases were issued on Jan 8 in conjunction with the American Astronomical Society meeting in New Orleans. The releases describe a study of the supernova remnant Cassiopeia A (Cas A) using data from the Chandra X-ray Observatory and James Webb Space Telescope and include the first image of Cas A combining data from both telescopes. A hitherto-puzzling feature in Cas A referred to as the “Green Monster” because of its resemblance to the wall in the left field of Fenway Park has been traced to the blast wave from the exploding star that created Cas A impacting gas ejected from the star prior to the explosion. For details see: https://chandra.si.edu/press/24_releases/press_010824.html

Further Chandra press and image releases were issued on Jan 11, also in conjunction with the American Astronomical Society meeting in New Orleans. The releases describe a study of the brightest and most massive class of galaxies in the universe, called brightest cluster galaxies, in the centers of 95 clusters of galaxies that are themselves an extreme sample — the most massive clusters in a large survey using the South Pole Telescope. Combining Chandra data with additional observations from several ground-based radio and optical telescopes revealed that the trigger for stars to form in the galaxies examined is an amount of disordered motion in the hot gas — a physical concept called "entropy" — that falls below a critical threshold. Under this threshold, the hot gas inevitably cools to form new stars. For details see: https://chandra.harvard.edu/press/24_releases/press_011124.html

The schedule of targets for the next week is shown below and includes observations of SDSSJ101152.98+5442, which was accepted as a Target of Opportunity on Dec 19, an observation of AT2020yw coordinated with VLA, and an observation of SN2015da coordinated with VLA.