GCN Circular 10496

M. Stamatikos (OSU/NASA/GSFC), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
S. Campana (INAF-OAB), A. de Ugarte Postigo (INAF-OAB),
P. A. Evans (U Leicester), J. M. Gelbord (PSU),
C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
R. Margutti (Univ Bicocca&OAB), F. E. Marshall (NASA/GSFC),
S. R. Oates (UCL-MSSL), C. Pagani (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
P. Romano (INAF-IASFPA), B. Sbarufatti (INAF-OAB/IASFPA),
R. L. C. Starling (U Leicester) and T. N. Ukwatta (GSFC/GWU) report on
behalf of the Swift Team:

At 12:44:50 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 100316D trigger=416135).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 107.615, -56.278 which is 
   RA(J2000)  =  07h 10m 28s
   Dec(J2000) = -56d 16' 40"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  This is an image trigger, but there is a
possibility that there is a low-level peak about 100 sec long. 

The XRT began observing the field at 12:47:08.1 UT, 137.7 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 107.6291, -56.2567 which is equivalent to:
   RA(J2000)  = 07h 10m 30.98s
   Dec(J2000) = -56d 15' 24.1"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 81 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 2.38e-09 erg cm-2 s-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 148 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. Because part of the 2.7'x2.7'
sub-image was not received, the overlap with the XRT error circle is uncertain. 
The coverage of the XRT error circle by the 8'x8' region for the list of
sources generated on-board is uncertain because the large number of sources
filled the available telemetry. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.12. 

Burst Advocate for this burst is M. Stamatikos (Michael.Stamatikos-1 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.)