[vsnet-grb-info 25815] GRB 200612A: Swift detection of a burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27915
SUBJECT: GRB 200612A: Swift detection of a burst
DATE:    20/06/12 05:06:28 GMT
FROM:    David Palmer at LANL  <palmer at lanl.gov>

E. Sonbas (Adiyaman Univ.), C. Gronwall (PSU), N. J. Klingler (PSU),
H. A. Krimm (NSF), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester),
D. M. Palmer (LANL), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 04:39:37 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 200612A (trigger=977310).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 302.681, -45.357 which is 
   RA(J2000) = 20h 10m 43s
   Dec(J2000) = -45d 21' 24"
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 40 sec.  There is possible lower-level
activity out to T+180s.  The peak count rate was ~1400 counts/sec 
(15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 04:41:04.7 UT, 87.7 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 302.7017, -45.3343 which is equivalent to:
   RA(J2000)  = 20h 10m 48.41s
   Dec(J2000) = -45d 20' 03.5"
with an uncertainty of 5.1 arcseconds (radius, 90% containment). This
location is 97 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy. 

The initial flux in the 2.5 s image was 2.13e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 95 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
0.03. 

We note that Fermi-GBM sees a GRB in a similar location at T+10 minutes,
(trigger  613630183) which may be extended activity of the same source. 
At that time, BAT had slewed away from the source. 

Burst Advocate for this burst is E. Sonbas (edasonbas AT yahoo.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/)