[vsnet-grb-info 17890] GRB 160424A: Swift-XRT observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19336
SUBJECT: GRB 160424A: Swift-XRT observations
DATE:    16/04/24 13:09:41 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at leicester.ac.uk>

P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows
(PSU), J.A. Kennea (PSU), M. Perri (ASDC) and G. Tagliaferri (INAF-OAB)
report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 160424A at 12:40:02.1 UT,
3054.8 seconds after the BAT trigger. Using promptly downlinked data we
find a fading, uncatalogued X-ray source located at RA, Dec 319.48505,
-60.41481 which is equivalent to:
   RA(J2000)  = 21h 17m 56.41s
   Dec(J2000) = -60d 24' 53.3"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 36 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 (3.94 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 2.5
(+2.04/-1.82) x 10^21 cm^-2 (90% confidence).