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
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