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GCN Circular 33207

Subject
GRB 230116C: Swift-XRT observations
Date
2023-01-23T13:54:57Z (a year ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J. D. Gropp (PSU), S. Dichiara (PSU), A.P. Beardmore (U. Leicester),
J.P. Osborne (U. Leicester), B. Sbarufatti (INAF-OAB), A. D'Ai
(INAF-IASFPA), A. Melandri (INAF-OAB), J.A. Kennea (PSU) and A. Y. Lien
(U Tampa) report on behalf of the Swift-XRT team:

We have analysed 9.4 ks of Photon Counting (PC) mode XRT data for the
Swift-BAT-detected burst GRB 230116C (Lien et al. GCN Circ. 33193),
collected between T0+159.6 ks and T0+537.9 ks. 

Six uncatalogued X-ray sources have been detected consistent with being
within 296 arcsec of the Swift-BAT position, 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):  223.47316  =  14:53:53.56
  Dec (J2000.0): -16.91649  =  -16:54:59.4
  Error: 2.7 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.0102 +/- 0.0013 ct s^-1   
  Distance: 167 arcsec from Swift-BAT position.
  Flux: (3.43 [+0.44, -0.43])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000.0):  223.4729  =  14:53:53.49
  Dec (J2000.0): -16.8864  =  -16:53:11.2
  Error: 6.4 arcsec (radius, 90% conf.)
  Count-rate: (2.80 [+1.09, -0.88])e-3 ct s^-1	 
  Distance: 65 arcsec from Swift-BAT position.

Source 3:
  RA (J2000.0):  223.4516  =  14:53:48.38
  Dec (J2000.0): -16.9158  =  -16:54:56.8
  Error: 6.8 arcsec (radius, 90% conf.)
  Count-rate: (3.15 [+0.84, -0.69])e-3 ct s^-1	 
  Distance: 165 arcsec from Swift-BAT position.
  Flux: (1.45 [+0.39, -0.32])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 8:
  RA (J2000.0):  223.4602  =  14:53:50.44
  Dec (J2000.0): -16.8420  =  -16:50:31.2
  Error: 6.3 arcsec (radius, 90% conf.)
  Count-rate: (1.79 [+0.90, -0.70])e-3 ct s^-1	 
  Distance: 104 arcsec from Swift-BAT position.

Source 9:
  RA (J2000.0):  223.4090  =  14:53:38.16
  Dec (J2000.0): -16.9156  =  -16:54:56.0
  Error: 8.1 arcsec (radius, 90% conf.)
  Count-rate: (8.7 [+5.4, -4.3])e-4 ct s^-1   
  Distance: 245 arcsec from Swift-BAT position.

Source 15:
  RA (J2000.0):  223.4391  =  14:53:45.37
  Dec (J2000.0): -16.8309  =  -16:49:51.2
  Error: 8.7 arcsec (radius, 90% conf.)
  Count-rate: (5.7 [+4.3, -3.4])e-4 ct s^-1   
  Distance: 166 arcsec from Swift-BAT position.

Eleven uncatalogued sources were also detected too far from the GRB
position to be likely afterglow candidates.

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/01149250.

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