GCN Circular 16230

K. L. Page (U Leicester), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC),
J. A. Kennea (PSU), V. Mangano (PSU), C. B. Markwardt (NASA/GSFC),
F. E. Marshall (NASA/GSFC), C. J. Mountford (U Leicester),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Swift Team:

At 02:22:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140509A (trigger=598497).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 46.608, -62.654 which is 
   RA(J2000)  =  03h 06m 26s
   Dec(J2000) = -62d 39' 12"
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 30 sec.  The peak count rate
was ~1200 counts/sec (15-350 keV), at ~4 sec after the trigger. 

The XRT began observing the field at 02:24:06.1 UT, 112.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 46.5952,
-62.6396 which is equivalent to:
   RA(J2000)  = 03h 06m 22.84s
   Dec(J2000) = -62d 38' 22.6"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 55 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.23 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.6
(+2.56/-2.25) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 5.99e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 250 seconds with the U filter starting
279 seconds after the BAT trigger. There is a candidate afterglow in the list
of sources generated on-board at
 RA(J2000)  =	03:06:22.67 =  46.59444
 DEC(J2000) = -62:38:21.7  = -62.63937
with a 90%-confidence error radius of about 1.10 arc sec. This position is 1.7
arc sec. from the center of the XRT error circle. The estimated magnitude is
16.24. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.02. 

Burst Advocate for this burst is K. L. Page (kpa AT star.le.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.)