GCN Circular 16177

D. Kocevski (NASA/GSFC/ORAU), S. D. Barthelmy (GSFC),
A. Y. Lien (NASA/GSFC/ORAU), D. Malesani (DARK/NBI),
C. B. Markwardt (NASA/GSFC) and D. M. Palmer (LANL) report on behalf
of the Swift Team:

At 22:40:50 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140428A (trigger=597519).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 194.342, +28.357, which is 
   RA(J2000)  =  12h 57m 22s
   Dec(J2000) = +28d 21' 26"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  Most of the expected realtime products were
not available for this trigger so we have limited information.   We 
know that the trigger duration is 4 seconds and the image significance
is 9 sigma during that exposure.  A light curve is not yet available. 

We note that the position reported in TDRSS light curve notices are 
incorrect.  The position reported above is correct. 

Because of outage in the TDRSS telemetry downlink,
all but one BAT light curve notice and all of the XRT notices
are missing.  Only a pair of UVOT SourceList and Image notices were 
received on the ground. 

However, based on the strong detection in BAT, we believe that this is
most likely a real GRB.  We will issue a Circular when the full dataset
is downlinked. 

Burst Advocate for this burst is D. Kocevski (dankocevski AT gmail.com). 
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.)