TITLE:   GCN CIRCULAR
NUMBER:  27079
SUBJECT: GRB 200215A: Swift detection of a burst
DATE:    20/02/15 15:14:13 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB), J.D. Gropp (PSU),
J. A. Kennea (PSU), N. J. Klingler (PSU), H. A. Krimm (NSF),
N. P. M. Kuin (UCL-MSSL), S. Laha (GSFC/UMBC/CRESST),
A. Melandri (INAF-OAB), K. L. Page (U Leicester), D. M. Palmer (LANL),
T. Sbarrato (INAF-OAB) and M. H. Siegel (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 14:39:31 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 200215A (trigger=956639).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 34.122, +12.781 which is 
   RA(J2000) = 02h 16m 29s
   Dec(J2000) = +12d 46' 50"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve up to T+8s showed a 
single-peaked structure with a duration of about 20 sec.  (The light curve
after T+8s is not immediately available.)  The peak count rate
was ~4000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 14:40:59.0 UT, 87.1 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 34.0794,
12.7704 which is equivalent to:
   RA(J2000)  = 02h 16m 19.05s
   Dec(J2000) = +12d 46' 13.6"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 154 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
https://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 (1.21 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 4.2
(+3.73/-3.12) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 90 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 0.15. 

Burst Advocate for this burst is M. G. Bernardini (grazia.bernardini AT brera.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/)