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GRB 081203A: Swift UVOT captures the earliest ultraviolet spectrum of a gamma-ray burst

Authors :
Kuin, N.
Landsman, W.
Page, M.
Schady, P.
Still, M.
Breeveld, A.
De Pasqualea, M.
Roming, P.
Brown, P.
carter, M.
James, C.
Curran, Peter
Cucchiara, A.
Gronwall, C.
Holland, S.
Hoversten, E.
Hunsberger, S.
Kennedy, T.
Koch, S.
Lamoureux, H.
Marshall, F.
Oates, S.
Parsons, A.
Palmer, D.
Smith, P.
Kuin, N.
Landsman, W.
Page, M.
Schady, P.
Still, M.
Breeveld, A.
De Pasqualea, M.
Roming, P.
Brown, P.
carter, M.
James, C.
Curran, Peter
Cucchiara, A.
Gronwall, C.
Holland, S.
Hoversten, E.
Hunsberger, S.
Kennedy, T.
Koch, S.
Lamoureux, H.
Marshall, F.
Oates, S.
Parsons, A.
Palmer, D.
Smith, P.
Publication Year :
2009

Abstract

We present the earliest ultraviolet (UV) spectrum of a gamma-ray burst (GRB) as observedwith the Swift Ultra-Violet/Optical Telescope (UVOT). The GRB 081203A spectrum wasobserved for 50 s with the UV-grism starting 251 s after the Swift-Burst-Alert-Telescope(BAT) trigger. During this time, the GRB was ˜13.4 mag (u filter) and was still rising to itspeak optical brightness. In the UV-grism spectrum, we find a damped Lya line, Lyß and theLyman continuum break at a redshift z = 2.05 ± 0.01. A model fit to the Lyman absorptionimplies a gas column density of log NHI = 22.0 ± 0.1 cm-2, which is typical of GRB hostgalaxies with damped Lya absorbers. This observation of GRB 081203A demonstrates thatfor brighter GRBs (v ˜ 14 mag) with moderate redshift (0.5 < z < 3.5) the UVOT is able toprovide redshifts, and probe for damped Lya absorbers within 4–6 min from the time of theSwift-BAT trigger.

Details

Database :
OAIster
Publication Type :
Electronic Resource
Accession number :
edsoai.on1033946843
Document Type :
Electronic Resource

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