GCN Circular 28023

A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), T.
Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini
(INAF-OAB), D.N. Burrows (PSU) and P.A. Evans (U. Leicester) report on
behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Swift/BAT-detected burst GRB 200623A (James DeLaunay et al. GCN Circ.
28013
Not found
 
 
), collecting 5.0 ks of Photon Counting (PC) mode data between
T0+37.8 ks and T0+50.1 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 1:
  RA (J2000.0):  242.2874  =  16:09:8.97
  Dec (J2000.0): +53.5321  =  +53:31:55.6
  Error: 4.4 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (3.5 [+1.2, -1.0])e-3 ct s^-1   
  Distance: 406 arcsec from Swift/BAT position.
  Flux: (1.09 [+0.39, -0.32])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)


Source 2:
  RA (J2000.0):  242.1106  =  16:08:26.55
  Dec (J2000.0): +53.3466  =  +53:20:47.9
  Error: 5.1 arcsec (radius, 90% conf.)
  Count-rate: (1.19 [+0.79, -0.56])e-3 ct s^-1	 
  Distance: 462 arcsec from Swift/BAT position.

Source 3:
  RA (J2000.0):  241.9966  =  16:07:59.18
  Dec (J2000.0): +53.4786  =  +53:28:42.8
  Error: 5.0 arcsec (radius, 90% conf.)
  Count-rate: (3.10 [+1.11, -0.91])e-3 ct s^-1	 
  Distance: 272 arcsec from Swift/BAT position.
  Flux: (1.96 [+0.70, -0.58])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)


Source 1 is consistent with a known quasar, [VV2006] J160908.9+533153.
Source 2 is poorly detected and is likely to be a background 
fluctuation.
Source 3 is not a known X-ray source, its position is consistent with a
background galaxy, SDSS J160758.62+532842.2 (D'Avanzo et al., GCN
#28021).

Follow up observation of source 3 are planned to be carried out at the
end of this week.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021005.

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