[vsnet-grb-info 19153] GRB 170222A: Swift-XRT observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20729
SUBJECT: GRB 170222A: Swift-XRT observations
DATE:    17/02/23 16:51:35 GMT
FROM:    Antonino D'Ai at IASF-PA  <antonino.dai at ifc.inaf.it>

A. D'Ai (IASF-PA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V.
D'Elia (ASDC), S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester)
and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the IPN-detected
burst GRB 170222A in a series of observations tiled on the sky and
covering the entire IPN error box. The total exposure time is 5.3 ks,
distributed over 3 tiles; the maximum exposure at a single sky location
was 3.2 ks. The data were collected between T0+33.8 ks and T0+38.9 ks,
and are entirely in Photon Counting (PC) mode.

Three uncatalogued X-ray sources are detected:

Source 1:
   RA (J2000.0):    292.95293 = 19h 31m 48.70s
   Dec (J2000.0):   28.04614  = +28:02:46.1
   Error: 5.0 arcsec
   Count-rate:	 1.01 (+0.21, -0.20) × 10-2 ct/s

Source 2:
   RA (J2000.0):    292.68930 = 19h 30m 45.43s	
   Dec (J2000.0):    27.96842 = +27:58:06.3
   Error: 5.7 arcsec
   Count-rate: 2.4 (+0.9, -0.7) × 10-2 ct/s

Source 3:
   RA (J2000.0):    293.02439 = 19h 32m 05.85s	
   Dec (J2000.0):    28.26746 = +28:16:02.9
   Error: 3.1 arcsec
   Count-rate: 8.0 (+2.8, -2.3) ×10-3 ct/s

However, none of these is a credible afterglow candidate.
Source 2 is outside the IPN errorbox, while sources 1 and 3 match
Simbad sources NVSS J193148+280248 and CCDM J19321+2816BC. Sources 2
and 3 are affected by optical loading and might be spurious detections.

The Swift XRT observations did not cover the Fermi GBM error circle
reported by Hamburg et al. (GCN #20728).

The results of the full analysis of the tiled XRT observations are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00064.

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