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GCN Circular 36052

Swift Trigger 1220736: detection of 4U 1543-62.
2024-04-08T15:43:49Z (a month ago)
K.L. Page at U Leicester <>

R. Brivio (INAF-OAB), S. Dichiara (PSU), M. Ferro (INAF-OAB),
C. Gronwall (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU),
N. J. Klingler (GSFC/UMBC/CRESSTII), A. Y. Lien (U Tampa),
K. L. Page (U Leicester), C. Salvaggio (INAF-OAB),
T. Sbarrato (INAF-OAB) and B. Sbarufatti (INAF-OAB) report on behalf
of the Neil Gehrels Swift Observatory Team:

At 15:13:54 UT, the Swift Burst Alert Telescope (BAT) triggered 
on 4U 1543-62 (trigger=1220736).  Swift slewed immediately to the source. 
The BAT on-board calculated location is 
RA, Dec 236.947, -62.534 which is 
   RA(J2000) = 15h 47m 47s
   Dec(J2000) = -62d 32' 01"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 10 sec.  The peak count rate
was ~300 counts/sec (15-350 keV), at ~4 sec after the trigger. 

The XRT began observing the field at 15:16:08.0 UT, 133.4 seconds after
the BAT trigger. XRT found a bright X-ray source located at RA, Dec
236.9760, -62.5656 which is equivalent to:
   RA(J2000)  = 15h 47m 54.24s
   Dec(J2000) = -62d 33' 56.2"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 123 arcseconds from the BAT onboard position, within the
BAT error circle. This position is 7.6 arcseconds from the known source 
4U 1543-62. No event data are yet available to determine the column density
using X-ray spectroscopy. 

The initial flux in the 2.5 s image was 5.62e-09 erg cm^-2 s^-1 (0.2-10

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 141 seconds after the BAT trigger. A source
consistent with the location of 4U 1543-62 is detected. 

This source is a known Low Mass X-ray Binary, also known by the name QU TrA. 

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