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GCN Circular 22723

Subject
GRB 180514A: Swift detection of a burst
Date
2018-05-14T13:48:36Z (6 years ago)
From
Boris Sbarufatti at PSU <bxs60@psu.edu>
S. J. LaPorte (PSU), A. P. Beardmore (U Leicester),
A. A. Breeveld (UCL-MSSL), D. N. Burrows (PSU), A. Deich (PSU),
S. W. K Emery (UCL-MSSL), J.D. Gropp (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
B. Sbarufatti (PSU), M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report
on behalf of the Neil Gehrels Swift Observatory Team:

At 13:25:33 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180514A (trigger=832368).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 197.401, +36.969 which is 
   RA(J2000) = 13h 09m 36s
   Dec(J2000) = +36d 58' 10"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 40 sec.  The peak count rate
was ~1300 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 13:26:51.3 UT, 77.8 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 197.3713,
36.9720 which is equivalent to:
   RA(J2000)  = 13h 09m 29.12s
   Dec(J2000) = +36d 58' 19.3"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 86 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.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.18
x 10^20 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 1.69e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 86 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
0.01. 

The first BAT Position notice identified this trigger as a transient
from a known source because of proximity with the spiral galaxy NGC
5005. However, given the separation between the XRT position and NGC
5005 (~18 arcmin) and the look of the promptly downlinked BAT and XRT
data we believe this is a GRB not associated with the foreground
galaxy. 

Burst Advocate for this burst is S. J. LaPorte (extragsam 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.)
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