GCN Circular 43435

R. Gupta (NASA GSFC) and K. L. Page (U Leicester) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 06:28:58 UT, the Swift Burst Alert Telescope (BAT) triggered and
located the HMXB 1A 1118-61 (trigger 1441823). Swift slewed soon after 
the event. The BAT on-board calculated location is 
RA, Dec 170.183, -61.905 which is 
   RA(J2000) = 11h 20m 44s
   Dec(J2000) = -61d 54' 17"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure.  This is an image-triggered event.

The XRT began observing the field at 06:35:17.6 UT, 378.7 seconds after
the BAT trigger. XRT found a bright X-ray source located at RA, Dec
170.2403, -61.9170 which is equivalent to:
   RA(J2000)  = 11h 20m 57.67s
   Dec(J2000) = -61d 55' 01.2"
with an uncertainty of 5.5 arcseconds (radius, 90% containment). This
location is 106 arcseconds from the BAT onboard position, within the
BAT error circle. This position is 4.3 arcseconds from a known X-ray
source: LSXPS J112057.1-615459. This source is in the Swift XRT LSXPS 
catalogue with a mean 0.3-10 keV count-rate of 0.2537 +/- 0.0012
ct/sec; see https://www.swift.ac.uk/LSXPS/LSXPS%20J112057.1-615459 for
details of these previous observations. No event data are yet available
to determine the column density using X-ray spectroscopy.

This trigger occurred just as Swift was exiting the SAA, so it is not
clear at this time whether the source has actually brightened, or if
the trigger was caused by the enhanced particle background.