GCN Circular 1214
Subject
Optical polarization observations for GRB011211
Date
2002-01-01T20:47:03Z (23 years ago)
From
Stefano Covino at Brera Astronomical Observatory <covino@merate.mi.astro.it>
S. Covino, G. Ghisellini, P. Saracco, G. Tagliaferri, F. Zerbi
(Observ. of Brera, Milan, Italy); S. Di Serego, A. Cimatti (Observ. of Arcetri,
Florence, Italy); F. Fiore, G.L. Israel, L. Stella (Observ. of Monte Porzio,
Rome, Italy); N. Kawai (RICHEN, Japan); D. Lazzati (IoA, Cambridge, UK); S.
Ortolani (University of Padua, Italy); L. Pasquini (ESO, Garching, Munich,
Germany); G. Ricker (MIT, USA); R. Gilmozzi, E. Pompei (ESO, Paranal, Chile)
report:
On 2001 December 13.29 we observed the optical counterpart to the X-ray
rich GRB011211 that was reported by Grav et al. (GCN 1191). The observations
were performed with the ESO VLT-3 (Melipal) telescope equipped with FORS1
with a Bessel R band filter in the imaging polarimetry mode. The transient
source is clearly detected and the acquisition image allowed to derive the
Bessel V magnitude of the transient, V=21.81 +/- 0.06, with respect to the
USNO star U0675_11427359 (Henden, GCN 1197).
Polarimetric measurements were performed by means of PSF fitting and
aperture techniques for the optical transient and a number of field stars in
order to estimate the average Galactic dust induced field polarization.
The result is that the optical transient polarization is consistent with zero
within the observational uncertainties. We estimate an upper limit to the
linear polarization of the OT of about 2.5%. Further analyses are in progress.
A plot in the Q and U Stokes' vector plane for the field objects is shown at
the URL: http://www.merate.mi.astro.it/~covino/GRB011211/GRB_POL.jpg. The OT
is in red.
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