GCN Circular 23639
S. D. Barthelmy (GSFC), C. Gronwall (PSU), J. A. Kennea (PSU), H. A. Krimm (NSF/USRA), D. M. Palmer (LANL) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 01:21:53 UT, the Swift Burst Alert Telescope (BAT) triggered and located the new source MAXI J1631-479 (trigger=882561). Swift did not slew due an observing constraint. The BAT on-board calculated location is RA, Dec 247.810, -47.725, which is RA(J2000) = 16h 31m 14s Dec(J2000) = -47d 43' 28" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is typical for an image trigger, there is nothing visible in the real-time light curve. We confirm that Trigger 878548 on 2018-12-23 (D'Avanzo et al. GCN #23550) was also due to MAXI J1631-479 as reported by Miyasaka et al. (ATel #12340). BAT has been detecting this source continuously since discovery. XRT and UVOT observations are planned for when this source comes out of Sun constraint around January 14.