TITLE:   GCN CIRCULAR
NUMBER:  14842
SUBJECT: GRB 130610A: Swift detection of a burst with an optical counterpart
DATE:    13/06/10 03:21:59 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

J. R. Cummings (NASA/UMBC), D. N. Burrows (PSU),
N. Gehrels (NASA/GSFC), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), D. Malesani (DARK/NBI),
C. B. Markwardt (NASA/GSFC), A. Maselli (INAF-IASFPA),
A. Melandri (INAF-OAB), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. H. Siegel (PSU) and T. N. Ukwatta (MSU) report on behalf of the
Swift Team:

At 03:12:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130610A (trigger=557845).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 224.416, +28.191 which is 
   RA(J2000) = 14h 57m 40s
   Dec(J2000) = +28d 11' 28"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a total duration of about 30 sec.  The peak count rate
was ~2700 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 03:14:26.3 UT, 133.0 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 224.4218, 28.2048 which is equivalent to:
   RA(J2000)  = +14h 57m 41.23s
   Dec(J2000) = +28d 12' 17.3"
with an uncertainty of 6.6 arcseconds (radius, 90% containment). This
location is 52 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. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 140 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	14:57:40.89 = 224.42037
  DEC(J2000) = +28:12:25.7  =  28.20715
with a 90%-confidence error radius of about 0.62 arc sec. This position is 9.6
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.91 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.02. 

Burst Advocate for this burst is J. R. Cummings (jayc AT milkyway.gsfc.nasa.gov). 
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.)