TITLE:   GCN CIRCULAR
NUMBER:  19271
SUBJECT: GRB 160410A: Swift detection of a (possibly-short) burst with an optical counterpart
DATE:    16/04/10 05:35:57 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

S. L. Gibson (U Leicester), D. Malesani (DARK/NBI),
K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Swift Team:

At 05:09:48 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 160410A (trigger=682269).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 150.681, +3.443 which is 
   RA(J2000) = 10h 02m 43s
   Dec(J2000) = +03d 26' 37"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 2 sec.  The peak count rate
was ~9000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 05:11:10.9 UT, 82.9 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 150.6857, 3.4782 which is equivalent to:
   RA(J2000)  = +10h 02m 44.57s
   Dec(J2000) = +03d 28' 41.5"
with an uncertainty of 5.6 arcseconds (radius, 90% containment). This
location is 127 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 1.04e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 91 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
 RA(J2000)  =	10:02:44.39 = 150.68494
 DEC(J2000) = +03:28:42.9  =	3.47858
with a 90%-confidence error radius of about 0.78 arc sec. This position is 3.0
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.49 with a 1-sigma error of about  0.16. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.02. 

Burst Advocate for this burst is S. L. Gibson (slg44 AT 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.)