Optical observations of supernova 1993 J from la Palma-I. Days 2 to 125

Abstract

We present astrometric, photometric and spectroscopic observations of supernova 1993J in M81, obtained with the Isaac Newton Group telescopes and the Carlsberg Automatic Meridian Circle. The spectral data set includes the first spectrum ever taken of SN1993J. The early spectra also yield an estimate of the total visual extinction, Av. This is combined with the photometric data to produce a bolometric light curve. Implications of the latter and of the spectral development are also discussed. The spectral evolution includes an infrared excess, which appeared after day 50 and may be indicative of an IR echo. The unchanging nature of blueshifted oxygen lines in the spectra argues for asymmetry in the distribution of the line-emitting region.