GCN Circular 15157

D. Malesani (DARK/NBI), J. R. Cummings (NASA/UMBC),
N. Gehrels (NASA/GSFC), D. Grupe (PSU), C. J. Mountford (U Leicester),
M. H. Siegel (PSU) and T. N. Ukwatta (MSU) report on behalf of the
Swift Team:

At 09:13:17 UT, the Swift Burst Alert Telescope (BAT) triggered and
located possible GRB 130901A or a Galactic source (trigger=569022).  
Swift slewed immediately to the detected source position.  The BAT on-board 
calculated location is 
RA, Dec 263.611, -30.402 which is 
   RA(J2000) = 17h 34m 27s
   Dec(J2000) = -30d 24' 07"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve does not show significant 
variation, which is not unusual for an image-based trigger. 

The XRT began observing the field at 09:15:20.0 UT, 123.0 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 263.6018, -30.3961 which is equivalent to:
   RA(J2000)  = +17h 34m 24.43s
   Dec(J2000) = -30d 23' 46.0"
with an uncertainty of 5.3 arcseconds (radius, 90% containment). This
location is 35 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. 

The initial flux in the 0.1 s image was 3.68e-08 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 4 seconds with the White filter
starting 131 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image cover 100%
of the XRT error circle.  Results from the list of sources
generated on-board are not available at this time. 

This burst occurred at Galactic coordinates l = 357.47, b = 1.29, that
is only 2.8 deg away from the Galactic Center. At this stage, we
cannot confirm whether this is a Galactic or extragalactic transient. 

Burst Advocate for this burst is D. Malesani (malesani AT dark-cosmology.dk). 
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.)