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GCN Circular 32431

Subject
GRB 220730A: Swift detection of a short hard burst
Date
2022-07-30T16:05:05Z (2 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
S. Dichiara (PSU), J. A. Kennea (PSU),
N. J. Klingler (GSFC/UMBC/CRESSTII), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL),
A. Tohuvavohu (U Toronto) and M. A. Williams (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 15:48:55 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 220730A (trigger=1118357).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 225.021, -69.497 which is 
   RA(J2000) = 15h 00m 05s
   Dec(J2000) = -69d 29' 48"
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 0.2 sec.  The peak count rate
was ~10000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 15:50:43.0 UT, 108.2 seconds after
the BAT trigger. No source was detected in 446 s of promptly downlinked
data. We are waiting for the full dataset to detect and localise the
XRT counterpart. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 111 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. 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 91% of the
BAT 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
0.161. 

Burst Advocate for this burst is S. Dichiara (simonedichiara55 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/)
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