GCN Circular 37732

B. Sbarufatti (INAF-OAB), D.N. Burrows (PSU), M. A. Williams (PSU), S.
Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester),
C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB) and P.A. Evans report on
behalf of the Swift-XRT team:

We have analysed 7.8 ks of XRT data for GRB 241006A, from 295 s to 50.5
ks after the  BAT trigger. The data comprise 23 s in Windowed Timing
(WT) mode with the remainder in Photon Counting (PC) mode. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=3.3 (+0.4, -0.3).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.73 (+0.28, -0.20). The
best-fitting absorption column is  6.4 (+8.3, -1.5) x 10^20 cm^-2,
consistent with the Galactic value of 4.9 x 10^20 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 3.9 x 10^-11 (4.3 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     6.4 (+8.3, -1.5) x 10^20 cm^-2
Galactic foreground: 4.9 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.73 (+0.28, -0.20)

If the light curve continues to decay with a power-law decay index of
3.3, the count rate at T+24 hours will be 3.1 x 10^-8 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x
10^-18 (1.3 x 10^-18) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01258721.

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