GCN Circular 16642

C. B. Markwardt (NASA/GSFC), M. G. Bernardini (INAF-OAB),
P. D'Avanzo (INAF-OAB), N. Gehrels (NASA/GSFC),
F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB) and
D. M. Palmer (LANL) report on behalf of the Swift Team:

At 19:43:51 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140730A (trigger=607742).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 56.431, -66.539 which is 
   RA(J2000) = 03h 45m 43s
   Dec(J2000) = -66d 32' 19"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 5 sec (FWHM ~2-3 sec)  The peak 
count rate was ~1800 counts/sec (15-350 keV), at ~1 sec after the 
trigger. 

The XRT began observing the field at 19:44:55.1 UT, 63.8 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 56.39573, -66.54597 which is equivalent
to:
   RA(J2000)  = 03h 45m 34.98s
   Dec(J2000) = -66d 32' 45.5"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 56 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.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 7.59
x 10^20 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 68 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 0.09. 

Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt 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.)