GCN Circular 11363

C. J. Saxton (UCL-MSSL), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
M. M. Chester (PSU), J. R. Cummings (NASA/UMBC),
M. De Pasquale (UCL-MSSL), N. Gehrels (NASA/GSFC),
J. M. Gelbord (PSU), S. T. Holland (CRESST/USRA/GSFC),
J. A. Kennea (PSU), O. M. Littlejohns (U Leicester),
C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),
S. R. Oates (UCL-MSSL), K. L. Page (U Leicester), D. M. Palmer (LANL),
M. Stamatikos (OSU/NASA/GSFC), R. L. C. Starling (U Leicester) and
E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team:

At 22:50:12 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 101023A (trigger=436981).  Swift slewed immediately to the 
burst.
The BAT on-board calculated location is
RA, Dec 317.954, -65.394 which is
    RA(J2000) = 21h 11m 49s
    Dec(J2000) = -65d 23' 37"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty).  The lightcurve shows a small initial pulse at 
T+0
seconds with a large FRED pulse at about T+55 sec. The peak flux was
32000 counts/sec at T+55 sec.

The XRT began observing the field at 22:51:36.9 UT, 84.5 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 317.9704, -65.3859 which is equivalent to:
    RA(J2000)  = 21h 11m 52.89s
    Dec(J2000) = -65d 23' 09.2"
with an uncertainty of 5.3 arcseconds (radius, 90% containment). This
location is 37 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 100 seconds with the White
filter  starting 92 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  0.03. The XRT position lies 10.6" from a catalogued USNO
object, photometry is difficult due to the bright halo of the 13th
magnitude USNO star. More data is required to determine if a new
source is present.

Burst Advocate for this burst is C. J. Saxton (cjs2@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.)