TITLE:   GCN CIRCULAR
NUMBER:  6958
SUBJECT: GRB 071021: Swift detection of a burst
DATE:    07/10/21 09:56:46 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

T. Sakamoto (NASA/UMBC), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
N. Gehrels (NASA/GSFC), C. Guidorzi (Univ Bicocca&INAF-OAB),
C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester),
J. P. Osborne (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), P. Romano (Univ. Bicocca & INAF-OAB) and
S. D. Vergani (DIAS-DCU) report on behalf of the Swift Team:

At 09:41:33 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 071021 (trigger=294974).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 340.636, +23.707 which is 
   RA(J2000)  =  22h 42m 33s
   Dec(J2000) = +23d 42' 24"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As with most 64 second image triggers,
there is no obvious variation in the count rate light curve. 

The XRT began observing the field at 09:43:44 UT, 130 seconds after the
BAT trigger. XRT found a bright, uncatalogued X-ray source
located at RA, Dec 340.6445, +23.7185 which is
   RA(J2000)  =  22h 42m 34.6s
   Dec(J2000) =  23d 43' 06.5"
with an uncertainty of 6.0 arcseconds (radius, 90% containment). 
This location is 50 arcseconds from the BAT on-board position,
within the BAT error circle. The initial flux in the 2.5s image
was 3.2e-09 erg/cm2/s (0.2-10 keV). 

UVOT is still in engineering mode after the gyro restorations, so there
will be no data products for this trigger. 

Burst Advocate for this burst is T. Sakamoto (takanori 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.)