[vsnet-grb-info 11997] Swift detection of IGR J17062-6143

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13386
SUBJECT: Swift detection of IGR J17062-6143
DATE:    12/06/25 23:03:17 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at milkyway.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
D. N. Burrows (PSU), J. A. Kennea (PSU), A. Melandri (INAF-OAB),
D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and
C. A. Swenson (PSU) report on behalf of the Swift Team:

At 22:42:31 UT, the Swift Burst Alert Telescope (BAT) triggered and
located IGR J17062-6143 (trigger=525148).  Swift slewed immediately to the source. 
The BAT on-board calculated location is 
RA, Dec 256.609, -61.728 which is 
   RA(J2000)  =  17h 06m 26s
   Dec(J2000) = -61d 43' 40"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is typical with image triggers (duration = 64 sec),
the real-time lightcurve does not show anything significant. 

The XRT began observing the field at 22:45:05.2 UT, 153.6 seconds after
the BAT trigger. XRT found a bright X-ray source located
at RA, Dec 256.5681, -61.7098 which is equivalent to:
   RA(J2000)  = +17h 06m 16.34s
   Dec(J2000) = -61d 42' 35.3"
with an uncertainty of 5.7 arcseconds (radius, 90% containment). This
location is 95 arcseconds from the BAT onboard position, within the BAT
error circle. 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 2.25e-08 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 250 seconds with the U filter starting
321 seconds after the BAT trigger. There is a candidate afterglow in the
rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	17:06:16.27 = 256.56779
  DEC(J2000) = -61:42:40.0  = -61.71112
with a 90%-confidence error radius of about 0.61 arc sec. This position is 4.8
arc sec. from the center of the XRT error circle. The estimated magnitude is
15.84 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.15. 

IGR J17062-6143 is a known X-ray transient with a location of 
RA=256.56771, DEC=-61.71125 (RA=17 06 16.3, DEC=-61 42 40.5)
with an uncertainty of 0.3 arc sec (ATEL #1840; Ricci et al.),
consistent with this detection. 

The nature of this transient is unknown and further observation
are warranted.