GCN Circular 28980

M. Perri (ASDC), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Tohuvavohu
(U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU), J.P. Osborne (U.
Leicester), K.L. Page (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
Swift/BAT-detected burst GRB 201128B (James DeLaunay et al. GCN Circ.
28971
Not found
 
 
), collecting 5.0 ks of Photon Counting (PC) mode data between
T0+246.0 ks and T0+303.8 ks. 

Ten 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):  339.4164  =  22:37:39.94
  Dec (J2000.0): -49.2698  =  -49:16:11.1
  Error: 5.1 arcsec (radius, 90% conf.)
  Count-rate: (3.32 [+1.13, -0.93])e-3 ct s^-1	 
  Distance: 169 arcsec from Swift/BAT position.
  Flux: (1.67 [+0.57, -0.47])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000.0):  339.0250  =  22:36:5.99
  Dec (J2000.0): -49.1319  =  -49:07:54.7
  Error: 5.2 arcsec (radius, 90% conf.)
  Count-rate: (4.7 [+2.8, -2.0])e-3 ct s^-1   
  Distance: 876 arcsec from Swift/BAT position.

Source 4:
  RA (J2000.0):  339.5648  =  22:38:15.55
  Dec (J2000.0): -49.2141  =  -49:12:50.9
  Error: 7.7 arcsec (radius, 90% conf.)
  Count-rate: (2.35 [+1.05, -0.81])e-3 ct s^-1	 
  Distance: 508 arcsec from Swift/BAT position.
  Flux: (7.8 [+3.5, -2.7])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 5:
  RA (J2000.0):  339.4267  =  22:37:42.42
  Dec (J2000.0): -49.1173  =  -49:07:02.2
  Error: 5.3 arcsec (radius, 90% conf.)
  Count-rate: (1.36 [+0.77, -0.57])e-3 ct s^-1	 
  Distance: 494 arcsec from Swift/BAT position.
  Flux: (9.5 [+5.4, -4.0])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 6:
  RA (J2000.0):  339.2905  =  22:37:9.71
  Dec (J2000.0): -49.3858  =  -49:23:08.7
  Error: 5.1 arcsec (radius, 90% conf.)
  Count-rate: (6.6 [+2.0, -1.6])e-3 ct s^-1   
  Distance: 524 arcsec from Swift/BAT position.
  Flux: (1.69 [+0.50, -0.42])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 7:
  RA (J2000.0):  339.2768  =  22:37:6.43
  Dec (J2000.0): -49.1392  =  -49:08:21.0
  Error: 4.9 arcsec (radius, 90% conf.)
  Count-rate: (4.7 +/- 1.3)e-3 ct s^-1	 
  Distance: 425 arcsec from Swift/BAT position.
  Flux: (2.03 +/- 0.55)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 8:
  RA (J2000.0):  339.2888  =  22:37:9.31
  Dec (J2000.0): -49.1961  =  -49:11:45.9
  Error: 7.2 arcsec (radius, 90% conf.)
  Count-rate: (2.17 [+0.97, -0.77])e-3 ct s^-1	 
  Distance: 236 arcsec from Swift/BAT position.
  Flux: (1.84 [+0.83, -0.65])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 9:
  RA (J2000.0):  339.2747  =  22:37:5.92
  Dec (J2000.0): -49.1221  =  -49:07:19.5
  Error: 9.8 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (3.04 [+1.19, -0.95])e-3 ct s^-1	 
  Distance: 483 arcsec from Swift/BAT position.
  Flux: (7.4 [+2.9, -2.3])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 10:
  RA (J2000.0):  339.5188  =  22:38:4.51
  Dec (J2000.0): -49.1801  =  -49:10:48.4
  Error: 6.9 arcsec (radius, 90% conf.)
  Count-rate: (1.89 [+0.94, -0.72])e-3 ct s^-1	 
  Distance: 454 arcsec from Swift/BAT position.
  Flux: (3.0 [+1.5, -1.1])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 11:
  RA (J2000.0):  339.5043  =  22:38:1.04
  Dec (J2000.0): -49.3084  =  -49:18:30.2
  Error: 5.2 arcsec (radius, 90% conf.)
  Count-rate: (2.14 [+1.07, -0.81])e-3 ct s^-1	 
  Distance: 418 arcsec from Swift/BAT position.
  Flux: (1.04 [+0.52, -0.39])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

A catalogued source was also detected.

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/00021044.

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