GCN Circular 16216

K.L. Page, P.A. Evans and B.P. Gompertz (U Leicester) report on behalf
of the Swift-XRT team:

We have analysed 7.7 ks of XRT data for GRB 140506A (Gompertz  et al.
GCN Circ. 16214
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 ),  from 87 s to 30.4 ks after the  BAT trigger. The
data comprise 531 s in Windowed Timing (WT) mode (the first 9 s were
taken while Swift was slewing) with the remainder in Photon Counting
(PC) mode. The enhanced XRT position for this burst was given by
Osborne et al. (GCN Circ. 16215
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 ).

The late-time light curve (from T0+5.1 ks) can be modelled with  a
power-law decay with a decay index of alpha=0.91 (+/-0.08).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 2.65 (+/-0.03). The
best-fitting absorption column is  3.14 (+/-0.10) x 10^21 cm^-2, in
excess of the Galactic value of 1.1 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.79 (+/-0.09) and a
best-fitting absorption column of 2.9 (+/-0.4) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.2 x 10^-11 (5.6 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     2.9 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: 7.6 sigma
Photon index:	     1.79 (+/-0.09)

If the light curve continues to decay with a power-law decay index of
0.91, the count rate at T+24 hours will be 0.058 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.4 x
10^-12 (3.2 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00598284.

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