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arXiv · 0812.2943

Swift-UVOT captures the earliest ultraviolet spectrum of a Gamma Ray Burst

N. P. M. Kuin·W. B. Landsman·M. J. Page·P. Schady·M. Still·A. A. Breeveld·M. De Pasquale·P. J. Brown·M. Carter·C. James·P. A. Curran·A. Cucciara·C. Gronwall·S. T. Holland·E. A. Hoversten·S. Hunsberger·T. Kennedy·S. Koch·H. Lamoureux·F. E. Marshall·S. R. Oates·A. Parsons·D. Palmer·P. Roming·P. J. Smith
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Abstract

We present the earliest ever ultraviolet spectrum of a gamma-ray burst (GRB) as observed with the Swift-UVOT. The GRB 081203A spectrum was observed for 50 seconds with the UV grism starting 251 seconds after the Swift-BAT trigger when the GRB was of u ~13.4 mag and still rising to its peak optical brightness. The UV grism spectrum shows a damped Ly-alpha line, Ly-beta, and the Lyman continuum break at a redshift z = 2.05 +/- 0.01. A model fit to the Lyman absorption implies log N(HI) = 22.0 +/- 0.2 cm-2, which is typical for GRB host galaxies with damped Ly-alpha absorbers. This observation of GRB 081203A demonstrates that for GRBs brighter than v ~14 mag and with 0.5 < z < 3.5 the UVOT will be able to provide redshifts, and probe for damped Ly-alpha absorbers within 4-6 minutes from the time of the Swift-BAT trigger.

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N. P. M. Kuin, W. B. Landsman, M. J. Page, P. Schady, M. Still, A. A. Breeveld, M. De Pasquale, P. J. Brown, M. Carter, C. James, P. A. Curran, A. Cucciara, C. Gronwall, S. T. Holland, E. A. Hoversten, S. Hunsberger, T. Kennedy, S. Koch, H. Lamoureux, F. E. Marshall, S. R. Oates, A. Parsons, D. Palmer, P. Roming, P. J. Smith. 2009-01-28. Swift-UVOT captures the earliest ultraviolet spectrum of a Gamma Ray Burst. https://doi.org/10.1111/j.1745-3933.2009.00632.x

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