GCN Circular 8292

T. Sakamoto (NASA/UMBC), S. D. Barthelmy (GSFC),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), C. Gronwall (PSU),
C. Guidorzi (INAF-OAB), S. T. Holland (CRESST/USRA/GSFC),
J. Mao (INAF-OAB), F. E. Marshall (NASA/GSFC),
P. T. O'Brien (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), A. M. Parsons (GSFC) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:

At 15:01:32 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 080928 (trigger=326115).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 95.084, -55.173 which is 
   RA(J2000) = 06h 20m 20s
   Dec(J2000) = -55d 10' 23"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  This is an image trigger so as usual
the BAT lightcurve shows nothing. 

The XRT began observing the field at 15:04:22.6 UT, 169.7 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 95.0691, -55.1997 which is equivalent to:
   RA(J2000)  = 06h 20m 16.58s
   Dec(J2000) = -55d 11' 58.9"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 100 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 5.77e-09 erg cm^-2 s^-1 (0.2-10
keV). 


UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 179 seconds after the BAT trigger. There is a candidate
afterglow in the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	06:20:16.85 =  95.0702
  DEC(J2000) = -55:11:59.3  = -55.1998
with a 1-sigma error radius of about 0.5 arc sec. This position is 2.3 arc sec. 
from the center of the XRT error circle. The estimated magnitude is 19.2 with a
1-sigma error of about 0.5 mag. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.07. 




Burst Advocate for this burst is T. Sakamoto (Taka.Sakamoto AT 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.)