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GCN Circular 31749

Subject
GRB 220310C: Swift-XRT observations
Date
2022-03-12T22:45:55Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
D.N. Burrows (PSU), J. D. Gropp (PSU), J.P. Osborne (U. Leicester),
K.L. Page (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo
(INAF-OAB), M.G. Bernardini (INAF-OAB), 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
Swift/BAT-GUANO-detected burst GRB 220310C, collecting 4.6 ks of Photon
Counting (PC) mode data between T0+102.8 ks and T0+120.2 ks. 

Four 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):  289.9580  =  19:19:49.91
  Dec (J2000.0): +40.2093  =  +40:12:33.3
  Error: 7.9 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (4.4 +/- 1.2)e-3 ct s^-1	 
  Distance: 344 arcsec from Swift/BAT-GUANO position.
  Flux: (9.6 +/- 2.7)e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000.0):  290.2354  =  19:20:56.50
  Dec (J2000.0): +40.3333  =  +40:19:59.9
  Error: 7.6 arcsec (radius, 90% conf.)
  Count-rate: (3.7 [+1.4, -1.1])e-3 ct s^-1   
  Distance: 539 arcsec from Swift/BAT-GUANO position.
  Flux: (1.39 [+0.51, -0.42])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 3:
  RA (J2000.0):  290.1544  =  19:20:37.05
  Dec (J2000.0): +40.2064  =  +40:12:23.0
  Error: 6.3 arcsec (radius, 90% conf.)
  Count-rate: (1.92 [+0.98, -0.76])e-3 ct s^-1	 
  Distance: 288 arcsec from Swift/BAT-GUANO position.
  Flux: (4.2 [+2.2, -1.7])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 4:
  RA (J2000.0):  289.8727  =  19:19:29.46
  Dec (J2000.0): +40.2572  =  +40:15:26.0
  Error: 6.4 arcsec (radius, 90% conf.)
  Count-rate: (1.41 [+0.96, -0.69])e-3 ct s^-1	 
  Distance: 540 arcsec from Swift/BAT-GUANO position.

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/00021483.

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