GCN Circular 19735

J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL),
T. G. R. Roegiers (PSU) and B. Sbarufatti (INAF-OAB/PSU) report on
behalf of the Swift Team:

At 01:27:51 UT, the Swift Burst Alert Telescope (BAT) triggered and
located PSR J1119-6127 (trigger=706396).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 169.828, -61.477 which is 
   RA(J2000) = 11h 19m 19s
   Dec(J2000) = -61d 28' 38"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single spike
structure with a duration of about 0.1 sec.  The peak count rate
was ~8000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 01:28:53.8 UT, 62.8 seconds after
the BAT trigger. Using promptly downlinked data we find an X-ray source
with an enhanced position: RA, Dec 169.8088, -61.4634 which is
equivalent to:
   RA(J2000)  = 11h 19m 14.11s
   Dec(J2000) = -61d 27' 48.3"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
position may be improved as more data are received; the latest position
is available at http://www.swift.ac.uk/sper. This position is 1.2
arcseconds from that of a known X-ray source: 3XMM J111914.2-612749 in
the XMM-NEWTON XMMSSC catalogue. The catalogued count-rate of this
source is equivalent to approximately 0.0049 XRT count/sec; the mean
count-rate in the promptly-available XRT data is 0.31 count/sec

A power-law fit to a spectrum formed from promptly downlinked event
data does not constrain the column density. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 67 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 large, but uncertain extinction expected. 

This burst looks like the burst from a Soft Gamma Repeater,
although this is the first onboard detection of this source in the 
BAT history.  The pulsar is categorized as a high magnetic field pulsar, 
(see, e.g., Antonopoulou et al. MNRAS 447, 3924�3935 (2015)) with a
field comparable or a little below the definition of a magnetar. 
Its period is less than half a second, similar but less than most 
SGR/AXP/magnetars that are previously known to produce bursts. 
It is not in the McGill online magnetar catalog. 

This burst places the pulsar in the same general category.