Letter to the Editor

Optical polarimetry of SN 2004bv^*

Departamento de Astronomia, IAG, Universidade de São Paulo, Rua do Matão 1226, São Paulo, SP 05508-900, Brazil e-mail: antonio@astro.iag.usp.br

Received: 13 December 2004
Accepted: 28 January 2005

Abstract

We report R band imaging polarimetry of SN 2004bv in NGC 6907 on June 19.299 (UT middle of observation), i.e., two weeks after maximum. We have obtained [ 0.11 ± 0.02] % at position angle 1187 for the observed polarization. The average foreground polarization from field objects was estimated to be [ 0.12 ± 0.02] % at PA 1634, consistent with the low reddening towards the SN. Spectroscopy reported elsewhere does not show the Na I D line in the SN spectrum suggesting that the interstellar polarization in the host galaxy is negligible. If this is the case, the data are consistent with SN 2004bv being close to spherically symmetric. The estimated R magnitude at the time of the observations was 14.5 mag. An upper limit to the SN H magnitude on June 20.259 (UT) was 13.9 mag. The role that small and medium-sized telescopes may play in studying the symmetry and time evolution of SN explosions is pointed out.