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GCN Circular 17722

Subject
GRB 150418A: Swift-XRT observations
Date
2015-04-18T20:33:05Z (9 years ago)
From
Boris Sbarufatti at INAF-OAB/IASFPA <boris.sbarufatti@brera.inaf.it>
B. Sbarufatti (INAF-OAB/PSU), A. Amaral-Rogers (U. Leicester), J.P.
Osborne (U. Leicester), K.L. Page (U. Leicester), P. D'Avanzo
(INAF-OAB), V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA), D.N.
Burrows (PSU), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) report
on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the MAXI-detected
burst GRB 150418A (Serino et al. GCN Circ. 17719) in a series of
observations tiled on the sky. The total exposure time is 3.7 ks,
distributed over 7 tiles; the maximum exposure at a single sky location
was 1.5 ks. The data were collected between T0+12.9 ks and T0+32.6 ks,
and are entirely in Photon Counting (PC) mode. 

Two uncatalogued X-ray sources have been detected, however none of them
is above the RASS limit or shows definitive signs of fading. Therefore,
at the present time we cannot identify which, if any, is the afterglow.
Details of these sources are given below:

Source 1:
  RA (J2000.0):  160.2608  =  10:41:2.60
  Dec (J2000.0): -4.7593  =  -04:45:33.5
  Error: 6.4 arcsec (radius, 90% conf.)
  Count-rate: 0.0124 [+0.0060, -0.0047] ct s^-1
  Flux: (5.0 [+2.4, -1.9])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000.0):  160.6825  =  10:42:43.80
  Dec (J2000.0): -5.3357  =  -05:20:08.4
  Error: 5.8 arcsec (radius, 90% conf.)
  Count-rate: 0.0215 [+0.0089, -0.0074] ct s^-1
  Flux: (8.6 [+3.6, -3.0])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00041.

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