[vsnet-grb-info 26756] GRB 201104A: Swift-XRT observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28859
SUBJECT: GRB 201104A: Swift-XRT observations
DATE:    20/11/06 17:46:49 GMT
FROM:    Boris Sbarufatti at PSU  <bxs60 at psu.edu>

V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D.
Gropp (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), J.P.
Osborne (U. Leicester), A. Melandri (INAF-OAB) and P.A. Evans (U.
Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 201104A (Ohno et al. GCN Circ. 28828) in a
series of observations tiled on the sky. The total exposure time is 4.7
ks, distributed over 3 tiles; the maximum exposure at a single sky
location was 2.4 ks. The data were collected between T0+67.6 ks and
T0+80.9 ks, and are entirely in Photon Counting (PC) mode. 

One uncatalogued X-ray source has been detected, it is not above the
RASS limit or shows definitive signs of fading. Furthermore, it is
coincident with a known optical source and the XRT data are possibly
affected by stray light. Therefore we believe that XRT has not detected
any viable candidate afterglow.
Details of the sources are given below:

Source 3:
  RA (J2000.0):  80.9041  =  05:23:36.99
  Dec (J2000.0): -71.0096  =  -71:00:34.6
  Error: 4.1 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (5.3 [+2.7, -2.0])e-3 ct s^-1   
  Distance: 664 arcsec from Fermi/LAT position.
  Flux: (1.53 [+0.77, -0.59])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)


A catalogued source was also detected inside the LAT error circle, and
two more sources were detected outside of it.

The 3 sigma upper limit at the LAT GRB position is 7.6×10-3 ct s-1.

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00094.

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