[vsnet-grb-info 3741] GRB 060919: Swift detection of a burst

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5575
SUBJECT: GRB 060919: Swift detection of a burst
DATE:    06/09/19 08:18:59 GMT
FROM:    David Palmer at LANL  <palmer at lanl.gov>

C. Guidorzi (Univ Bicocca&INAF-OAB), S. D. Barthelmy (GSFC),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), C. Gronwall (PSU),
J. A. Kennea (PSU), H. A. Krimm (GSFC/USRA), V. Mangano (INAF-IASFPA),
A. Moretti (INAF-OAB), K. L. Page (U Leicester), D. M. Palmer (LANL),
P. Romano (INAF-OAB) and S. D. Vergani (DIAS-DCU) report on behalf of
the Swift Team:

At 07:48:38 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 060919 (trigger=230115).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA,Dec 276.911, -51.028 {18h 27m 39s, -51d 01' 38"} (J2000)
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked 
structure with an initial main peak of duration ~ 2 sec and lower level 
emission out to T+20 sec.  This is followed by a second peak at T+ ~300 sec
of duration ~30 sec seen only in the 15-50 keV band.  The peak 
count rate was ~2500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began taking data at 07:50:05 UT, 87 seconds after the BAT
trigger. The XRT on-board centroid algorithm did not find a source in the
image. 
Ground analysis reveals a possible faint source at the following coordinates:   
RA(J2000): 18h 27m 42.35s
Dec(J2000): -51 00 51.2   
with an error of 5.1 arcseconds (90% confidence). Further analysis of 
ground data is necessary to determine the properties of the possible
source. The current flux is 8.3x10^-9 erg cm-2 s-1. 

UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 91 seconds after the BAT trigger. No
afterglow candidate has been found in the initial data products. The
overlap of the 8'x8' region for the list of sources generated
on-board and the BAT error circle is 100%. No correction has
been made for the expected extinction corresponding to E(B-V) of
0.07.