[vsnet-grb-info 4852] GRB 070628: Swift detection of a possible burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6584
SUBJECT: GRB 070628: Swift detection of a possible burst
DATE:    07/06/28 15:01:09 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

S. T. Holland (CRESST/GSFC/USRA), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), P. J. Brown (PSU),
D. N. Burrows (PSU), S. Campana (INAF-OAB), M. L. Conciatore (ASDC),
N. Gehrels (NASA/GSFC), C. Gronwall (PSU),
C. Guidorzi (Univ Bicocca&INAF-OAB), J. A. Kennea (PSU),
H. A. Krimm (GSFC/USRA), V. La Parola (INAF-IASFPA),
V. Mangano (INAF-IASFPA), F. E. Marshall (NASA/GSFC),
P. T. O'Brien (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), M. Perri (ASDC),
P. Romano (Univ. Bicocca & INAF-OAB), T. Sakamoto (NASA/ORAU),
G. Sato (GSFC/ISAS), M. Stamatikos (NASA/ORAU) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:

At 14:41:02 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 070628 (trigger=283320).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 115.284, -20.285 which is 
   RA(J2000)  =  07h 41m 08s
   Dec(J2000) = -20d 17' 04"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
on a rising background while entering the SAA with a duration of about 20 sec. 
The peak count rate was ~3000 counts/sec (15-350 keV), at ~5 sec after the
trigger.  Given the galactic latitude of +1.25deg, we can not rule out
a Galactic transient origin of this trigger. 

The XRT began taking data at 14:42:53 UT, 111 seconds after the BAT
trigger. The initial image mode frames show many cosmic ray tracks
due to entrance into the SAA; the XRT on-board centroid algorithm did
not find a source in the image and no prompt position is available. 
Further XRT data are delayed by the SAA passage. We are waiting for
down-linked data to detect and determine a position for the source. 

Because Swift was entering the SAA, there were no prompt UVOT
observations of this source. 

Burst Advocate for this burst is S. T. Holland (sholland 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.)