[vsnet-grb-info 10385] GRB 110328A: Swift detection of a burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11823
SUBJECT: GRB 110328A: Swift detection of a burst
DATE:    11/03/28 13:32:29 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at milkyway.gsfc.nasa.gov>

J. R. Cummings (NASA/UMBC), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
S. Campana (INAF-OAB), V. D'Elia (ASDC), P. A. Evans (U Leicester),
N. Gehrels (NASA/GSFC), J. M. Gelbord (PSU), C. Guidorzi (U Ferrara),
S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
O. M. Littlejohns (U Leicester), R. Margutti (INAF-OAB),
F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
C. Pagani (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), P. Romano (INAF-IASFPA), M. H. Siegel (PSU),
E. Sonbas (GSFC/USRA/Adiyaman Univ.), R. L. C. Starling (U Leicester),
G. Stratta (ASDC), G. Tagliaferri (INAF-OAB) and
E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team:

At 12:57:45 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110328A (trigger=450158).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 251.233, +57.590 which is 
   RA(J2000)  =  16h 44m 56s
   Dec(J2000) = +57d 35' 25"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is typical for 20-min long image triggers,
the BAT lightcurve does not show anything significant. 

The XRT began observing the field at 13:22:19.8 UT, 1474.6 seconds
after the BAT trigger. XRT found a bright, uncatalogued X-ray source
located at RA, Dec 251.2054, +57.5808 which is equivalent to:
   RA(J2000)  = 16h 44m 49.29s
   Dec(J2000) = +57d 34' 50.8"
with an uncertainty of 6.3 arcseconds (radius, 90% containment). This
location is 62 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. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 1482 seconds after the BAT trigger. No credible afterglow candidate
has been found in the initial data products. The 2.7'x2.7' sub-image covers
100% of the XRT error circle. The typical 3-sigma upper limit has been about
19.6 mag. The 8'x8' region for the list of sources generated on-board covers
100% of the XRT error circle. The list of sources is typically complete to
about 18 mag. No correction has been made for the expected extinction
corresponding to E(B-V) of 0.02. 

Burst Advocate for this burst is J. R. Cummings (jayc 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.)