TITLE:   GCN CIRCULAR
NUMBER:  25106
SUBJECT: GRB 190719C: Swift detection of a burst
DATE:    19/07/19 15:22:37 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

E. Ambrosi (INAF-IASFPA), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC),
J.D. Gropp (PSU), N. J. Klingler (PSU), H. A. Krimm (NSF),
N. P. M. Kuin (UCL-MSSL), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), B. Sbarufatti (PSU) and A. Tohuvavohu (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 14:58:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 190719C (trigger=915381).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 240.210, +12.977 which is 
   RA(J2000) = 16h 00m 50s
   Dec(J2000) = +12d 58' 39"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a total duration of about 100 sec.  The peak count rate
was ~6000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 14:59:35.3 UT, 60.9 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 240.20700,
12.99995 which is equivalent to:
   RA(J2000)  = 16h 00m 49.68s
   Dec(J2000) = +12d 59' 59.8"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 83 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 (4.69 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.9
(+3.40/-2.88) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 0.1 s image was 1.69e-08 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 71 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
0.04. 

The Fermi GBM team announced the detection of GRB 190719C (GCN Circ
25104).  Given the temporal coincidence, it is likely that this is the
same burst. 

Burst Advocate for this burst is E. Ambrosi (elena.ambrosi AT 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/)