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GCN Circular 24785

Subject
GRB 190611A: Swift detection of a burst
Date
2019-06-11T18:02:03Z (5 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
V. D'Elia (SSDC), J.D. Gropp (PSU), N. J. Klingler (PSU),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), M. J. Moss (GWU),
D. M. Palmer (LANL), B. Sbarufatti (PSU), M. H. Siegel (PSU) and
A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 17:49:01 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 190611A (trigger=907950).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 324.769, -56.082 which is 
   RA(J2000) = 21h 39m 05s
   Dec(J2000) = -56d 04' 54"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 10 sec.  The peak count rate
was ~900 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 17:50:55.4 UT, 113.5 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 324.72043, -56.07370 which
is equivalent to:
   RA(J2000)  = 21h 38m 52.90s
   Dec(J2000) = -56d 04' 25.3"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 102 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 (3.25 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.3
(+3.64/-3.06) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 116 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 none of
the XRT error circle. 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. 

Burst Advocate for this burst is V. D'Elia (delia AT ssdc.asi.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/)
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