Volume 513, April 2010
|Number of page(s)||7|
|Published online||22 April 2010|
GRB 090313: X-shooter's first shot at a gamma-ray burst*
INAF – Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate, Lc, Italy
2 European Southern Observatory, Casilla 19001, Santiago 19, Chile
3 APC – UMR 7164, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex, France
4 Service d'Astrophysique, DSM/IRFU/SAp, CEA-Saclay, 91191 Gif-sur-Yvette, France
5 INAF – Osservatorio Astronomico di Roma, Via Frascati, 33, 00040, Monteporzio Catone (Rome), Italy
6 ASI – Science Data Centre, Via Galileo Galilei, 00044 Frascati (Rome), Italy
7 Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
8 GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, 5 place Jules Janssen, 92195 Meudon, France
9 Astronomical Institute, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
10 European Southern Observatory, K. Schwarzschild Str. 2, 85748 Garching, Germany
11 INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
12 Department of Astrophysics, IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
13 INAF – IASF di Bologna, via Gobetti 101, 40129 Bologna, Italy
14 INAF – Osservatorio Astronomico di Trieste, via Tiepolo, 11, 34131 Trieste, Italy
15 Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
Accepted: 20 January 2010
Context. X-shooter is the first second-generation instrument to become operative at the ESO Very Large Telescope (VLT). It is a broad-band medium-resolution spectrograph designed with gamma-ray burst (GRB) afterglow spectroscopy as one of its main science drivers.
Aims. During the first commissioning night on sky with the instrument fully assembled, X-shooter observed the afterglow of GRB 090313 as a demonstration of the instrument's capabilities.
Methods. GRB 090313 was observed almost two days after the burst onset, when the object had already faded to R ~ 21.6. Furthermore, the 90% illuminated Moon was just 30 degrees away from the field. In spite of the adverse conditions, we obtained a spectrum that, for the first time in GRB research, simultaneously covers the range from 5700 to 23 000 Å.
Results. The spectrum shows multiple absorption features at a redshift of 3.3736, which we identify as the redshift of the GRB. These features are composed of 3 components with different ionisation levels and velocities. Some of the features have never been observed before in a GRB at such a high redshift. Furthermore, we detect two intervening systems at redshifts of 1.8005 and 1.9597.
Conclusions. These results demonstrate the potential of X-shooter in the GRB field, because it was capable of observing a GRB down to a magnitude limit that would include 72% of long GRB afterglows 2 h after the burst onset. Coupled with the rapid response mode available at VLT, allowing reaction times of just a few minutes, X-shooter constitutes an significant leap forward on medium resolution spectroscopic studies of GRBs, their host galaxies and intervening systems, probing the early history of the Universe.
Key words: gamma-ray burst: general / instrumentation: spectrographs
© ESO, 2010
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.