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

N.~P.~M. Kuin, W. Landsman, M.~J. Page, P. Schady, M. Still, A.~A. Breeveld, M. de Pasquale, P.~W.~A. Roming, P.~J. Brown, M. Carter, C. James, P.~A. Curran, A. Cucchiara, C. Gronwall, S.~T. Holland, E.~A. Hoversten, S. Hunsberger, T. Kennedy, S. Koch, H. LamoureuxF.~E. Marshall, S.~R. Oates, A. Parsons, D.~M. Palmer, P.~J. Smith

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Abstract

We present the earliest ultraviolet (UV) spectrum of a gamma-ray burst (GRB) as observed with the Swift Ultra-Violet/Optical Telescope (UVOT). The GRB 081203A spectrum was observed 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 its peak optical brightness. In the UV-grism spectrum, we find a damped Lyα line, Lyβ and the Lyman continuum break at a redshift z= 2.05 ± 0.01. A model fit to the Lyman absorption implies a gas column density of log NH i= 22.0 ± 0.1 cm−2, which is typical of GRB host galaxies with damped Lyα absorbers. This observation of GRB 081203A demonstrates that for brighter GRBs (v≈ 14 mag) with moderate redshift (0.5 < z < 3.5) the UVOT is able to provide redshifts, and probe for damped Lyα absorbers within 4–6 min from the time of the Swift-BAT trigger.
Original languageEnglish
Pages (from-to)L21-L24
JournalMonthly Notices of the Royal Astronomical Society
Volume395
Issue number1
DOIs
Publication statusPublished - 1 May 2009

Keywords

  • instrumentation: spectrographs, gamma-rays: bursts, Astrophysics

Cite this

Kuin, N. P. M., Landsman, W., Page, M. J., Schady, P., Still, M., Breeveld, A. A., de Pasquale, M., Roming, P. W. A., Brown, P. J., Carter, M., James, C., Curran, P. A., Cucchiara, A., Gronwall, C., Holland, S. T., Hoversten, E. A., Hunsberger, S., Kennedy, T., Koch, S., ... Smith, P. J. (2009). GRB 081203A: Swift UVOT captures the earliest ultraviolet spectrum of a gamma-ray burst. Monthly Notices of the Royal Astronomical Society, 395(1), L21-L24. https://doi.org/10.1111/j.1745-3933.2009.00632.x