TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1909 SUBJECT: GRB 030226: R band polarimetric observations DATE: 03/02/28 15:42:42 GMT FROM: Stefano Covino at Brera Astronomical Observatory S. Covino, G. Ghisellini, D. Malesani, G. Tagliaferri, F. Zerbi (INAF Brera, Italy); A. Cimatti, M. Della Valle, S. Di Serego (INAF Arcetri, Italy); F. Fiore, G.L. Israel, L. Stella (INAF Roma, Italy); E. Costa, P. Soffitta (IASF Roma, Italy), S. Mereghetti (IASF Milano, Italy), N. Kawai (Tokyo Tech, Japan); D. Lazzati (IoA, Cambridge, UK); S. Ortolani (Univ. of Padova, Italy); L. Pasquini (ESO, Germany); G. Ricker (MIT, USA); E. Le Floch, P. Goldoni, F. Mirabel (CEA, France), E. Mason, P.M. Vreeswijk (ESO Paranal), P. Price (RSAA, Australia), report: We observed the optical counterpart to GRB 030226 (Suzuki et al. GCN1888; Fox et al. GCN 1879) on February 27.261 (26.5 hours after the GRB trigger). The observations were performed with the ESO VLT-UT1 (Antu) telescope equipped with FORS1 and a Bessel R filter in the imaging polarimetry mode. The transient source is clearly detected in the acquisition frames with magnitudes: R = 20.64 +/- 0.02 at 27.212 UT and R = 20.79 +/- 0.02 at 27.261 UT. Magnitude are calibrated following Garnavich et al. (GCN 1885). Preliminary results for the analysis of the polarimetric frames in the R band yielded a very strict upper limit: P < 1.1% (95% confidence level) at 27.261 UT The observation was performed about 14 hours after the break identified in the afterglow lightcurve (Greiner et al. GCN 1894, Zeh et al. GCN 1898). See also http://www.sissa.it/~malesani/GRB/030226 . This message is citeable.