Spectropolarimetry of SN1987A: observations up to 1987 July 8

Spectropolarimetric observations of SN 1987 A in the LMC are presented. These are the first such observations of a supernova with a signal-to-noise ratio sufficient to show polarization variations across the spectral lines. Observations have been made at several epochs and cover a number of spectral regions; in most cases these include the region around Hα. In general the polarization through the lines is double peaked above a continuum value. We discuss in some detail the interstellar component in order to investigate its effect on the polarization profile. The presence of polarization shows that the supernova explosion was asymmetric. The axis and degree of asymmetry is dependent on wavelength. (author)