TITLE: GCN CIRCULAR NUMBER: 42289 SUBJECT: GRB 251014B: Swift-XRT observations DATE: 25/10/15 14:43:08 GMT FROM: Phil Evans at U of Leicester pae9@star.le.ac.uk
S. Lanava (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), A. Melandri (INAF-OAR), S. Dichiara (PSU), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the Fermi/GBM, Swift/BAT-GUANO-detected burst GRB 251014B, collecting 4.5 ks of Photon Counting (PC) mode data between T0+49.9 ks and T0+73.1 ks.
Three X-ray sources, of which two (Source 2 and Source 4) are uncatalogued, have been detected within the estimated 3-sigma Swift/BAT-GUANO error region (296 arcsec), 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 2: RA (J2000.0): 14.5787 = 00h 58m 18.89s Dec (J2000.0): -35.5678 = -35d 34' 04.2" Error: 7.3 arcsec (radius, 90% conf.) Count-rate: (2.66 [+1.09, -0.87])e-3 ct s^-1 Distance: 66 arcsec from Fermi/GBM position. Flux: (6.0 [+2.5, -2.0])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 3: RA (J2000.0): 14.6936 = 00h 58m 46.46s Dec (J2000.0): -35.5767 = -35d 34' 36.2" Error: 7.9 arcsec (radius, 90% conf.) Count-rate: (1.52 [+0.90, -0.66])e-3 ct s^-1 Distance: 287 arcsec from Fermi/GBM position. Source 3 matches the position of the quasar [VV98] J005846.6-353444.
Source 4: RA (J2000.0): 14.6178 = 00h 58m 28.28s Dec (J2000.0): -35.5331 = -35d 31' 59.2" Error: 6.2 arcsec (radius, 90% conf.) Count-rate: (1.87 [+0.98, -0.75])e-3 ct s^-1 Distance: 181 arcsec from Fermi/GBM position. Flux: (6.5 [+3.4, -2.6])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 4 is close to the 2MASS source J00582790-3531563 (5.4").
Another uncatalogued source (Source 1) was also detected, however this was too far from the GRB position to be the afterglow.
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/00021863.
This circular is an official product of the Swift-XRT team.
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