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GCN Circular 12859

Subject
GRB 120119A: Swift detection of a burst with an optical counterpart
Date
2012-01-19T04:22:23Z (12 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
A. P. Beardmore (U Leicester), S. D. Barthelmy (GSFC),
M. M. Chester (PSU), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (UCL-MSSL),
O. M. Littlejohns (U Leicester), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), M. H. Siegel (PSU), C. A. Swenson (PSU) and
T. N. Ukwatta (MSU) report on behalf of the Swift Team:

At 04:04:30.21 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 120119A (trigger=512035).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 120.027, -9.074, which is 
   RA(J2000)  =  08h 00m 07s
   Dec(J2000) = -09d 04' 25"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows at least three peaks
with a total duration of at least 50 sec.  The peak count rate
was ~16,000 counts/sec (15-350 keV), at ~10 sec after the trigger. 

The XRT began observing the field at 04:05:23.4 UT, 53.3 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 120.0293, -9.0803 which is equivalent to:
   RA(J2000)  = +08h 00m 7.03s
   Dec(J2000) = -09d 04' 49.1"
with an uncertainty of 4.7 arcseconds (radius, 90% containment). This
location is 24 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 2.5 s image was 1.06e-08 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 61 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	08:00:06.94 = 120.02890
  DEC(J2000) = -09:04:53.7  =  -9.08157
with a 90%-confidence error radius of about 0.66 arc sec. This position is 4.8
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.67 with a 1-sigma error of about  0.16. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.11. 

Burst Advocate for this burst is A. P. Beardmore (apb AT star.le.ac.uk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
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