GCN Circular 37421

R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), S. Dichiara (PSU), J.A.
Kennea (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P.
Beardmore (U. Leicester), A. Melandri (INAF-OAR) and P.A. Evans (U.
Leicester) reports on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 240905B, collecting 4.7 ks of Photon
Counting (PC) mode data between T0+165.8 ks and T0+184.5 ks. 

Six 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):  267.9656  =  17:51:51.73
  Dec (J2000.0): +14.3317  =  +14:19:54.0
  Error: 5.3 arcsec (radius, 90% conf.)
  Count-rate: (7.5 [+1.7, -1.6])e-3 ct s^-1   
  Distance: 489 arcsec from Fermi/LAT position.
  Flux: (1.21 [+0.28, -0.26])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000.0):  267.8714  =  17:51:29.15
  Dec (J2000.0): +14.1724  =  +14:10:20.6
  Error: 6.1 arcsec (radius, 90% conf.)
  Count-rate: (2.45 [+1.16, -0.91])e-3 ct s^-1	 
  Distance: 459 arcsec from Fermi/LAT position.

Source 3:
  RA (J2000.0):  268.0531  =  17:52:12.75
  Dec (J2000.0): +14.1172  =  +14:07:01.9
  Error: 6.3 arcsec (radius, 90% conf.)
  Count-rate: (1.14 [+0.99, -0.76])e-3 ct s^-1	 
  Distance: 351 arcsec from Fermi/LAT position.

Source 4:
  RA (J2000.0):  268.1019  =  17:52:24.47
  Dec (J2000.0): +14.0362  =  +14:02:10.2
  Error: 6.5 arcsec (radius, 90% conf.)
  Count-rate: (4.5 [+1.5, -1.3])e-3 ct s^-1   
  Distance: 688 arcsec from Fermi/LAT position.
  Flux: (1.10 [+0.38, -0.31])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 5:
  RA (J2000.0):  268.0524  =  17:52:12.56
  Dec (J2000.0): +14.2532  =  +14:15:11.5
  Error: 5.9 arcsec (radius, 90% conf.)
  Count-rate: (1.11 [+0.86, -0.69])e-3 ct s^-1	 
  Distance: 264 arcsec from Fermi/LAT position.

Source 6:
  RA (J2000.0):  267.9614  =  17:51:50.74
  Dec (J2000.0): +14.2308  =  +14:13:51.0
  Error: 7.4 arcsec (radius, 90% conf.)
  Count-rate: (1.41 [+0.93, -0.75])e-3 ct s^-1	 
  Distance: 174 arcsec from Fermi/LAT position.
  Flux: (3.8 [+2.5, -2.0])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

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/00021711.

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