GCN Circular 12228

M. De Pasquale (UCL-MSSL), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),
J. A. Kennea (PSU), A. Melandri (INAF-OAB),
C. J. Mountford (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), T. Sakamoto (NASA/UMBC),
B. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU),
E. Sonbas (GSFC/USRA/Adiyaman Univ.), C. A. Swenson (PSU),
E. Troja (NASA/GSFC/ORAU) and T. N. Ukwatta (MSU) report on behalf of
the Swift Team:

At 19:49:42 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110801A (trigger=458521).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 89.285, +80.988 which is 
   RA(J2000)  =  05h 57m 08s
   Dec(J2000) = +80d 59' 18"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a few weak peaks
with a duration of about 70 sec.  The peak count rate
was ~700 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 19:51:21.9 UT, 98.9 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 89.4307, +80.9548 which is equivalent to:
    RA(J2000)  = 05h 57m 43.36s
    Dec(J2000) = +80d 57' 17.2"
with an uncertainty of 4.9 arcseconds (radius, 90% containment). This
location is 146 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 108 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	05:57:44.73 =  89.43637
  DEC(J2000) = +80:57:21.6  =  80.95600
with a 90%-confidence error radius of about 0.62 arc sec. This position is 5.4
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.03 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.08. 

Burst Advocate for this burst is M. De Pasquale (mdp AT mssl.ucl.ac.uk). 
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.)