GCN Circular 7859

B. Sbarufatti, V. Mangano, V. La Parola (INAF-IASF Pa) report on  
behalf of
the Swift-XRT team.


Swift-XRT began observations of the field of GRB 080607 (trigger 313417,
Mangano et al., GCN circ. 7847
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 ) on date 2008 June 07, 06:08:54 UT, 87 s
after the BAT trigger. The data consist of 478 s in Windowed timing mode
and 3 ks in Photon Counting mode.

The lightcurve shows a complex behaviour. After an initial steep decay
(index 5.8 +/- 0.4) we observe a double peaked flare, starting at
T+ 118 (+/- 1) s and peaking at T+120 s and T+140 s. The underlying
decay breaks at T+ 119 (+ 5, - 2) s to a slope of 1.7 (+/- 0.1). A
second break at t+700 (+/- 300) marks the beginning of a plateau phase
(index 0.5 +/- 1.3). The lightcurve breaks again around
T+1600 (+/- 500) s, with a final decay index of -2.0 +/- 0.5.
The countrate predictions for T+24h and T+48h are 2.1E-3 counts/s
and 5.5E-4 count/s respectively.

The WT spectrum can be fit by a powerlaw with photon index 1.81 +/- 0.02
and an intrinsic absorbing column density of (4.0 +/- 0.2)E22 cm^-2 at
z=3.036 (Prochaska et al. GCN Circ. 7849
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 ), in excess with
respect to the Galactic value of 1.69E+20 cm^-2 (Kalberla et al. 2005).
The observed (unabsorbed) flux in the 0.3 - 10 keV band is
2.9 (3.0)E-9 erg cm^-2 s^-1.
The PC spectrum can be fit by a powerlaw with photon index 2.1 +/- 0.1
and an intrinsic absorbing column density of (4.0 +/- 0.8)E22 cm^-2 at
z=3.036, in excess with respect to the Galactic value. The observed
(unabsorbed) flux in the 0.3 - 10 keV band is
5.3 (5.4)E-11 erg cm^-2 s^-1.

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

[GCN OPS NOTE(08jun08): Per author's request, the "(4.0 +/- 0.8)E21"
was changed to "(4.0 +/- 0.8)E22".]