Аннотация:We present optical photometry and spectroscopy of the type IIP supernova SN 2004et that occurred in the nearby galaxy NGC 6946.The observations span a time range of 8 days to 541 days after explosion.The late time bolometric luminosity and the Hα luminosity in the nebular phase indicate that 0.06 ± 0.02M ⊙ of 56 Ni was synthesised during the explosion.The plateau luminosity, its duration and the expansion velocity of the supernova at the middle of the plateau indicate an explosion energy of E exp = 1.20 +0.38 -0.30 × 10 51 ergs.The late time light curve and the evolution of the [OI] and Hα emission line profiles indicate the possibility of an early dust formation in the supernova ejecta.The luminosity of [OI] 6300, 6364 Å doublet, before the dust formation phase, is found to be comparable to that of SN 1987A at similar epochs, impling an oxygen mass in the range 1.5 -2M ⊙ , and a main sequence mass of 20M ⊙ for the progenitor.
