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GCN Circular 18061

Trigger 650221: Swift detection of a IGR J00291+5934
2015-07-25T02:32:31Z (9 years ago)
Scott Barthelmy at NASA/GSFC <>
S. D. Barthelmy (GSFC), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC)
and T. Sakamoto (AGU) report on behalf of the Swift Team:

At 02:12:04 UT, the Swift Burst Alert Telescope (BAT) triggered and
located IGR J00291+5934 (trigger=650221).  Swift slewed immediately 
to the source location.  The BAT on-board calculated location is 
RA, Dec 7.256, +59.596 which is 
   RA(J2000)  =  00h 29m 01s
   Dec(J2000) = +59d 35' 45"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows weak and complex structure
with a duration of about 20 sec.  The peak count rate
was ~1281 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 02:14:04.4 UT, 119.5 seconds after
the BAT trigger. XRT found a bright X-ray source located at RA, Dec
7.2571, 59.5736 which is equivalent to:
   RA(J2000)  = +00h 29m 1.70s
   Dec(J2000) = +59d 34' 25.0"
with an uncertainty of 6.1 arcseconds (radius, 90% containment). This
position is 12.6 arcseconds from a known X-ray source: 1SXPS
J002903.1+593418. This source is in the Swift XRT 1SXPS catalogue with
a mean 0.3-10 keV count-rate of 1.740 +/- 0.037 ct/sec; see for details of
these previous observations. 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 1.57e-08 erg cm^-2 s^-1 (0.2-10

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 128 seconds after the BAT trigger. There is a candidate counterpart in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	00:29:03.06 =	7.26274
  DEC(J2000) = +59:34:19.2  =  59.57199
with a 90%-confidence error radius of about 0.62 arc sec. This position is 11.8
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.49 with a 1-sigma error of about  0.14. No correction has been made for the
large, but uncertain extinction expected.
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