TITLE:   GCN CIRCULAR
NUMBER:  7426
SUBJECT: GRB 080319A: Swift detection of a burst
DATE:    08/03/19 06:18:20 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

C. Pagani (PSU), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU),
C. B. Markwardt (CRESST/GSFC/UMD), D. M. Palmer (LANL),
J. L. Racusin (PSU) and M. Stamatikos (NASA/ORAU) report on behalf of
the Swift Team:

At 05:45:42 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 080319A (trigger=306754).  The Swift slew to the burst was
delayed because of an earth constraint. The BAT on-board calculated 
location is RA, Dec 206.354, +44.079 which is 
   RA(J2000) = 13h 45m 25s
   Dec(J2000) = +44d 04' 44"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multiple peaks
with a duration of about 40 sec.  The peak count rate
was ~800 counts/sec (15-350 keV), at ~10 sec after the trigger. 

The XRT began observing the field at 05:54:59.4 UT, 557.4 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 206.33306, 44.08029
which is equivalent to:
   RA(J2000)  = 13h 45m 19.94s
   Dec(J2000) = +44d 04' 49.1"
with an uncertainty of 2.6 arcseconds (radius, 90% containment). This
location is 54 arcseconds from the BAT onboard position, within the BAT
error circle. 

A power-law fit to a spectrum formed from promptly downlinked event
data does not constrain the column density, so we cannot provide limits
on the redshift using spectroscopy and the relation from Grupe et al. 
(2007). A summary of the promptly downlinked data is given at
http://www.swift.ac.uk/sper/306754/. 

UVOT took a finding chart exposure of 100 seconds with the White 
(160-650 nm)  filter starting 562 seconds after the BAT trigger. A 
possible low-significance afterglow candidate has  been found at the
XRT  position in the  initial data products.  The magnitude is white
= 21.7 mag.  No  correction has been made for the expected extinction
 corresponding to E(B-V) of  0.01. 

Burst Advocate for this burst is C. Pagani (pagani AT astro.psu.edu). 
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.)