V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA), D.N. Burrows (PSU),
J.A. Kennea (PSU), V. Mangano (PSU), P.A. Evans (U. Leicester), B.P.
Gompertz (U. Leicester), J.P. Osborne (U. Leicester), A. Maselli
(INAF-IASFPA) and L.M.Z. Hagen report on behalf of the Swift-XRT team:
We have analysed 10 ks of XRT data for GRB 141026A (Hagen et al. GCN
Circ. 16950), from 160 s to 46.2 ks after the BAT trigger. The data
comprise 49 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Beardmore et al. (GCN Circ. 16956).
The late-time light curve (from T0+3.5 ks) can be modelled with a
power-law decay with a decay index of alpha=0.35 (+0.11, -0.12).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.07 (+0.09, -0.08). The
best-fitting absorption column is 4.9 (+/-0.5) x 10^21 cm^-2, in
excess of the Galactic value of 1.6 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.92 (+0.28, -0.26)
and a best-fitting absorption column of 2.8 (+1.2, -1.0) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.8 x 10^-11 (5.4 x 10^-11) erg cm^-2
A summary of the PC-mode spectrum is thus:
Total column: 2.8 (+1.2, -1.0) x 10^21 cm^-2
Galactic foreground: 1.6 x 10^21 cm^-2
Excess significance: 2.0 sigma
Photon index: 1.92 (+0.28, -0.26)
If the light curve continues to decay with a power-law decay index of
0.35, the count rate at T+24 hours will be 0.023 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.9 x
10^-13 (1.2 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
This circular is an official product of the Swift-XRT team.