GCN Circular 8034

T. Sakamoto (NASA/UMBC), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), M. M. Chester (PSU),
N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC),
E. A. Hoversten (PSU), S. D. Hunsberger (PSU), J. A. Kennea (PSU),
C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL), A. M. Parsons (GSFC),
D. Perez (U Leicester), R. L. C. Starling (U Leicester) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:

At 22:31:19 UT, the Swift Burst Alert Telescope (BAT) triggered and
located XTE J1701-407 (trigger=318166).  Swift slewed immediately to the
transient. 
The BAT on-board calculated location is 
RA, Dec 255.478, -40.841 which is 
   RA(J2000)  = 17h 01m 55s
   Dec(J2000) = -40d 50' 26"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
with a duration of about 5 sec.  The peak count rate
was ~600 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 22:33:08.5 UT, 108.7 seconds after
the BAT trigger. XRT found a bright X-ray source located
at RA, Dec 255.4353, -40.8564 which is equivalent to:
   RA(J2000)  = 17h 01m 44.4s
   Dec(J2000) = -40d 51' 23.0"
with an uncertainty of 5.4 arcseconds (radius, 90% containment). This
location is 128 arcseconds from the BAT onboard position, within the
BAT error circle. This is 7.2 arcseconds from the previously determined 
UVOT-enhanced XRT position given in Starling and Evans, Atel 1621.  
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
(160-650 nm)  filter starting 120 seconds after the BAT trigger. No
optical transient has  been found in the initial data products. The
2.7'x2.7' sub-image covers 100% of  the XRT error circle. The 3-sigma
upper limit at the position of the XRT source is 19.3 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 large, but uncertain
extinction expected. 

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