1995A&AS..110..513B

The observations of SN 1993J in M 81, obtained at Asiago throughout the first year after explosion and consisting of about 80 photometric measurements and 40 spectra, are presented. The light curve has been found peculiar showing two maxima similar to SN 1987A but with a faster evolution. In the late phases, two regimes in the luminosity decline are identified, with the radioactive exponential tail setting in around day 150 and showing a rate of decline similar to that of SNIa. Although the absorption correction to be applied is still controversial, the intensity of the interstellar NaI lines indicates a moderately strong reddening which imply an absolute magnitude M_B=-17.6 at secondary maximum. Also the spectral evolution is peculiar with the type II signatures leaving place, a few weeks after the explosion, to those ones of type Ib, although some H emissions remain visible. High resolution profiles of forbidden OI lines reveal the presence of clumping in the ejecta.