[vsnet-grb-info 20999] GRB 180806A: Swift-XRT afterglow detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23097
SUBJECT: GRB 180806A: Swift-XRT afterglow detection
DATE:    18/08/07 22:15:00 GMT
FROM:    Antonino D'Ai at IASF-PA  <antonino.dai at ifc.inaf.it>

S.L. Gibson (U. Leicester), Z. Liu (NAOC / U. Leicester), V. D'Elia
(ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti
(INAF-OAB/PSU), D.N. Burrows (PSU), A. Tohuvavohu (PSU) and P.A. Evans
(U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/GBM-detected burst GRB 180806A (Malacaria et al. GCN Circ.
23095), collecting 1.8 ks of Photon Counting (PC) mode data between
T0+57.6 ks and T0+76.2 ks. 

Two uncatalogued X-ray sources are detected, of which one ("Source 1")
is fading with 3-sigma significance, and is therefore likely the GRB
afterglow.  The position of this source is RA, Dec=11.5536, +24.3370
which is equivalent to:

RA (J2000): 00:46:12.86
Dec(J2000): +24:20:13.2

with an uncertainty of 5.0 arcsec (radius, 90% confidence). 
This position is 1.3 arcsec from the Fermi/GBM position and 2.7 arcsec
from the OT position reported by Lipunov (GCN 23091) and Watson (GCN
23092).

The source is fading with alpha >2.2.

The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/ToO_GRBs/00020812/Source1.php.
The results of the full analysis of the XRT observations are available
at http://www.swift.ac.uk/ToO_GRBs/00020812.

This circular is an official product of the Swift-XRT team.