Last week the NuSTAR project received 212 proposals requesting observations through Cycle 12 of the annual General Observer (GO) program. This is the second highest number of proposals received, the most since 2017, and continues the  trend over the past few years of increasing numbers of proposals each year.  Cycle 12 introduced a new opportunity for joint observations with XRISM, in addition to continuing opportunities for joint observations with XMM-Newton and Swift.  NuSTAR time is also available through the annual Chandra, IXPE, Swift, XRISM, and XMM-Newton announcements of opportunity.  Over-subscriptions for regular observations and coordinated observations in Cycle 12 ranged between 3.1x and 5.4x.  Also this Cycle, NuSTAR officially offered the new, quicker automated Target-of-Opportunity (ToO) response which enables NuSTAR to be on-target within six hours of receiving a ToO trigger. There were 73 Cycle 12 ToO proposals, corresponding to a 5.6x over-subscription. The proposals will be reviewed by independent panels of experts in March, the results will be announced in April, and Cycle 12 NuSTAR observations will begin in June.

Author: Karl Forster (NuSTAR Science Operations Center Lead, Caltech)