[vsnet-grb-info 10250] GRB 110205A: detection of optical linear polarization from CAHA

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11696
SUBJECT: GRB 110205A: detection of optical linear polarization from CAHA
DATE:    11/02/11 11:05:19 GMT
FROM:    Javier Gorosabel at IAA-CSIC  <jgu at iaa.es>

J. Gorosabel (IAA-CSIC), R. Duffard (IAA-CSIC), P. Kubanek (IAA-CSIC & U. of Valencia), A. Guijarro (CAHA), report on behalf of a larger collaboration:

"We carried out optical linear polarization observations of the GRB 110205A afterglow (GCN Circ. 11629, Beardmore et al.) using the 2.2m telescope of the Calar Alto Observatory equipped with CAFOS. The data were acquired in the R-band on Feb 5.19879-5.26570 UT (2.73-4.33 hours post burst) with a total exposure time of 10x500s. A preliminary analysis reveals an afterglow linear polarization at a level of P~1.4%. This value is higher than the polarization (P ~< 0.4%) measured for the bright field stars, so we conclude that most of the measured afterglow polarization has very likely an extragalactic origin."