[AAVSO-HEN] GRB 080604: Swift-XRT refined analysis

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  7816
SUBJECT: GRB 080604: Swift-XRT refined analysis
DATE:    08/06/04 17:55:28 GMT
FROM:    Valentina La Parola at INAF-IASPA  <laparola at ifc.inaf.it>

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

The Swift-XRT observed GRB 080604 (trigger 313116, La Parola et
al. GCN Circ 7800) for 6.3 ksec, starting 119.3 seconds after
the BAT trigger.

We detect an X-ray counterpart at the position
(astrometrically corrected using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 236.96516, +20.55777 which is equivalent to:

RA (J2000): 15h 47m 51.64s
Dec (J2000): +20d 33' 28.0"

with an uncertainty of 1.7 arcsec (radius, 90% confidence).

The X-ray light curve shows a power law decay with slope -2.18 +/-0.06, with a hint of a flare at ~T+1000 s.

The spectrum accumulated over the whole observation can be modelled with an absorbed powerlaw with the following parameters (Galactic nH is
4.0e20cm**-2):

nH = (8 +/- 4)e20 cm**-2
Gamma= 1.8 +/- 0.2
Flux (0.3-10 keV) 4.18E-12 ergs cm**-2 s**-1
Unabsorbed Flux (0.3-10 keV) = 4.9E-12 ergs cm**-2 s**-1

The predicted XRT count rate after 24 hours from the burst is 1.5e-5
counts/s

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

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