TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  330
SUBJECT: GRB 990510: optical linear polarization
DATE:    99/05/17 11:51:55 GMT
FROM:    Gabriele Ghisellini at Obs.Astro. di Brera  <gabriele@merate.mi.astro.it>

S. Covino, D. Lazzati, G. Ghisellini, P. Saracco, S. Campana, G. Chincarini 
(Observ. of Brera, Milan, Italy); S. Di Serego, A. Cimatti (Observ. of 
Arcetri, Florence, Italy); L. Vanzi, L. Pasquini (ESO, Garching, Munich, 
Germany); F. Haardt (Univ. of Insubria, Como, Italy); M. Vietri (Univ. of 
Rome III, Italy); L. Stella (Observ. of Monte Porzio, Rome, Italy);
R. Falomo (Observ. of Padua, Italy); H. Boehnhardt, F. Bresolin, P. Moller,
G. Rupprecht (ESO-VLT service team), report:

We made imaging polarimetry of the optical transient associated to
GRB 990510 at ESO-VLT-FORS1 on 1999 May 11.13509, in the R band, when
the R-magnitude of the object was 19.1+/-0.02.
We found linear polarization at the level of 1.7+/-0.2 per cent with 
position angle 12+/-4 degrees, relative to the stars in the field.

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