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GCN Circular 5707

GRB 061007: Swift detection of a burst with an optical counterpart
2006-10-07T10:32:54Z (18 years ago)
Patricia Schady at MSSL/Swift <>
P. Schady (MSSL-UCL), J. R. Cummings (NASA/UMBC),
C. Guidorzi (Univ Bicocca&INAF-OAB), C. Pagani (PSU),
D. M. Palmer (LANL), S. B. Pandey (UCL-MSSL),
P. Romano (Univ. Bicocca & INAF-OAB), G. Sato (GSFC/ISAS),
M. Stamatikos (NASA/ORAU), L. Vetere (PSU) and
H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team:

At 10:08:08 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 061007 (trigger=232683).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA,Dec 46.318, -50.488 {03h 05m 16s, -50d 29' 15"} (J2000)
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 100 sec.  The peak count rate
was ~25000 counts/sec (15-350 keV), at ~54 sec after the trigger. 

The XRT began observing the field at 10:09:29 UT, 80 seconds after the
BAT trigger. XRT found a bright, fading, uncatalogued X-ray source
located at RA(J2000) = 03h 05m 19.5s, Dec(J2000) = -50d 30' 02.1",
with an estimated uncertainty of 7.5 arcseconds (90% confidence
radius). This location is 55 arcseconds from the BAT on-board
position, within the BAT error circle. The initial flux in the 0.1s
image was 3.4e-08 erg/cm2/s (0.2-10 keV). 

UVOT took a finding chart exposure of 400 seconds with the V filter
starting 195 seconds after the BAT trigger. There is a very bright
source in the 2.7' x 2.7' sub-image not present in DSS at RA(J2000) =
03:05:19.51 = 46.3313 DEC(J2000) = -50:30:02.5 = -50.5007 with a
1-sigma error radius of about 0.5 arc sec. This position is 0.7 arc
sec. from the center of the XRT error circle. The estimated magnitude
is 12.8 with a 1-sigma error of about 0.5 mag. No correction has been
made for the expected extinction of about 0.1 magnitudes.
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