TITLE:   GCN CIRCULAR
NUMBER:  17504
SUBJECT: GRB 150220A: Swift-XRT observations
DATE:    15/02/24 15:39:26 GMT
FROM:    Andrea Melandri at INAF-OAB  <andrea.melandri@brera.inaf.it>

V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA), A. Maselli 
(INAF-IASFPA), D.N. Burrows (PSU), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU), A.P. Beardmore (U. Leicester), A. Amaral-Rogers (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 150220A, collecting 3.0 ks of Photon Counting (PC) mode data
between T0+284.9 ks and T0+300.7 ks. 

Three 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 2:
  RA (J2000.0):  135.3781  =  09:01:30.74
  Dec (J2000.0): -1.6408  =  -01:38:27.0
  Error: 6.2 arcsec (radius, 90% conf.)
  Count-rate: (6.8 +/- 1.9)e-3 ct s^-1
  Flux: (3.26 +/- 0.93)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 3:
  RA (J2000.0):  135.5356  =  09:02:8.55
  Dec (J2000.0): -1.6164  =  -01:36:59.1
  Error: 4.9 arcsec (radius, 90% conf.)
  Count-rate: (4.7 +/- 1.7)e-3 ct s^-1
  Flux: (2.31 +/- 0.81)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 7:
  RA (J2000.0):  135.4432  =  09:01:46.37
  Dec (J2000.0): -1.6372  =  -01:38:13.9
  Error: 7.1 arcsec (radius, 90% conf.)
  Count-rate: (3.3 [+1.6, -1.3])e-3 ct s^-1
  Flux: (6.5 [+3.1, -2.5])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Four catalogued sources were also detected.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
http://www.swift.ac.uk/ToO_GRBs/00020484.

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