TITLE:   GCN CIRCULAR
NUMBER:  19547
SUBJECT: GRB 160622A: Swift detection of a possible short GRB or a new SGR
DATE:    16/06/22 02:38:47 GMT
FROM:    Caryl Gronwall at PSU/Swift-UVOT  <caryl@swift.psu.edu>

A. D'Ai (INAF-IASFPA), N. Gehrels (NASA/GSFC), C. Gronwall (PSU),
J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), A. Maselli (INAF-IASFPA),
T. Sakamoto (AGU) and M. H. Siegel (PSU) report on behalf of the Swift
Team:

At 02:03:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located possible GRB 160622A (trigger=700791).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 244.373, -51.045 which is 
   RA(J2000) = 16h 17m 30s
   Dec(J2000) = -51d 02' 41"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a short pulse
with a duration of about 0.1 sec.  The peak count rate
was ~4000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 02:04:44.8 UT, 91.1 seconds after
the BAT trigger. No source was detected in the 2.5-s promptly available
image. We are waiting for the full dataset to detect and localise the
XRT counterpart. 

UVOT took a finding chart exposure of	3 seconds with the White filter
starting 95 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 25% of
the BAT error circle. Because of the density of catalogued stars, further
analysis is required to report an upper limit for any afterglow in the
sub-image. Results from the list of sources generated on-board are not
available at this time. No correction has been made for the large, but
uncertain extinction expected. 

This source is at a low galactic latitude of -0.37 degrees and may be 
an SGR.  While the BAT lightcurve looks like a short GRB, it is not
dissimilar from an SGR.  We need the full  dataset to determine the
nature of this trigger. 

Burst Advocate for this burst is A. D'Ai (antonino.dai AT ifc.inaf.it). 
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.)