GCN Circular 7274

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
P. J. Brown (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC),
N. Gehrels (NASA/GSFC), E. A. Hoversten (PSU), J. A. Kennea (PSU),
D. M. Palmer (LANL), A. M. Parsons (GSFC), J. L. Racusin (PSU),
G. Sato (GSFC/ISAS), M. C. Stroh (PSU) and D. E. Vanden Berk (PSU)
report on behalf of the Swift Team:

At 20:32:05 UT, the Swift Burst Alert Telescope (BAT) triggered and
located the known source AX J1749.1-2639 (trigger=302788).  We note
that GCN ground software associated this to the GX 3+1 source,
but further analysis on the ground has determined this is really
the AX J1749.1-2639 source.  Swift slewed immediately to the source. 
The BAT on-board calculated location is 
RA, Dec 267.297, -26.643 which is 
   RA(J2000)  = 17h 49m 11s
   Dec(J2000) = -26d 38' 34"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  This was an image-trigger, so the TDRSS
lightcurve is of little value.  This source has been seen with increasing
activity for the last ~10 days and is currently at the 250 mCrab level. 

The XRT began observing the field at 20:34:02 UT, 117 seconds after the
BAT trigger. XRT found an X-ray source
located at RA, Dec 267.3046, -26.6437 which is
   RA(J2000)  =  17h 49m 13.1s
   Dec(J2000) = -26d 38' 37.3"
with an uncertainty of 5.0 arcseconds (radius, 90% containment)
which is consistant with the known source AX J1749.1-2639. 
This location is 25 arcseconds from the BAT on-board position,
within the BAT error circle.  The initial flux in the 2.5s image
was 1.9e-09 erg/cm2/s (0.2-10 keV). 

UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 123 seconds after the BAT trigger, and a
finding chart exposure of 248 seconds with the v filter starting 230
seconds after the trigger. No object is found at the XRT position. 
The 3-sigma upper limits at the XRT position are 18.7 mag (White) and
17.67 mag (v). Large, uncertain extinction is expected at this
position which is at low Galactic lattitude.