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Issue A&A
Volume 392, Number 3, September IV 2002
Page(s) 865 - 868
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20021025



A&A 392, 865-868 (2002)
DOI: 10.1051/0004-6361:20021025

Polarimetric observations of GRB 011211

S. Covino1, D. Lazzati2, D. Malesani1, G. Ghisellini1, G. L. Israel3, L. Stella3, A. Cimatti4, S. di Serego4, F. Fiore3, N. Kawai5, S. Ortolani6, L. Pasquini7, G. Ricker8, P. Saracco1, G. Tagliaferri1 and F. Zerbi1

1  Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (LC), Italy
2  Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA Cambridge, UK
3  Osservatorio Astronomico di Roma, via Frascati 33, Monteporzio Catone (Roma), Italy
4  Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
5  Dept. of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguroku, Tokyo 152-8551, Japan
6  Università di Padova, Dipartimento di Astronomia, Vicolo dell'Osservatorio 2, 35122 Padova, Italy
7  European Southern Observatory, Karl Schwarzschild Strasse 2, 85748 Garching bei München, Germany
8  Center for Space Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA

(Received 10 June 2002 / Accepted 11 July 2002 )

Abstract
We present and discuss polarimetric observations performed with the VLT-UT3 (Melipal) on the afterglow of GRB 011211, ~35 hours after the burst onset. The observations yielded a 3 $\sigma$ upper limit of $P<2.7\%$. We discuss this result in combination with the lightcurve evolution, that may show a break approximately at the time of our observation. We show that our upper limit is consistent with the currently favored beamed fireball geometry, especially if the line of sight was not too close to the edge of the cone.


Key words: gamma rays: bursts -- polarization -- radiation mechanisms: non-thermal

Offprint request: S. Covino, covino@merate.mi.astro.it

SIMBAD Objects in preparation



© ESO 2002


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