TITLE:   GCN CIRCULAR
NUMBER:  23776
SUBJECT: Trigger 885456: Swift detection of MAXI J1631-479
DATE:    19/01/24 03:34:41 GMT
FROM:    Aaron Tohuvavohu at PSU/Swift  <aaronb@swift.psu.edu>

V. D'Elia (SSDC), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester),
D. M. Palmer (LANL) and A. Tohuvavohu (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 03:17:21 UT, the Swift Burst Alert Telescope (BAT) triggered and
located MAXI J1631-479 (trigger=885456).  Swift slewed immediately to the target. 
The BAT on-board calculated location is 
RA, Dec 247.798, -47.808 which is 
   RA(J2000) = 16h 31m 11s
   Dec(J2000) = -47d 48' 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. 

The XRT began observing the field at 03:19:14.0 UT, 112.3 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 247.8092, -47.8066 which is equivalent to:
   RA(J2000)  = 16h 31m 14.21s
   Dec(J2000) = -47d 48' 23.8"
with an uncertainty of 5.3 arcseconds (radius, 90% containment), 
consistent with the known position of MAXI J1631-479. No event data 
are yet available to determine the column density using X-ray spectroscopy. 

The initial flux in the 0.1 s image was 3.90e-08 erg cm^-2 s^-1 (0.2-10
keV).