  We present densely-sampled UBVRI/griz photometric and low-resolution (6-10A)
optical spectroscopic observations from 4 to 270 days after explosion of a
newly discovered type II SN 2012aw in a nearby (~9.9 Mpc) galaxy M95. The
light-curve characteristics of apparent magnitudes, colors, bolometric
luminosity and the presence and evolution of prominent spectral features are
found to have striking similarity with the archetypal IIP SNe 1999em, 1999gi
and 2004et. The early time observations of SN 2012aw clearly detect minima in
the light-curve of V, R and I bands near 37 days after explosion and this we
suggest to be an observational evidence for emergence of recombination phase.
The mid-plateau MV magnitude (-16.67 $\pm$ 0.04) lies in between the bright (~
-18) and subluminous (~ -15) IIP SNe. The mass of nickel is 0.06$\pm$0.01
M_sun. The SYNOW modelling of spectra indicate that the value and evolution of
photospheric velocity is similar to SN 2004et, but about ~600 km/s higher than
that of SNe 1999em and 1999gi at comparable epochs. This trend is more apparent
in the line velocities of H alpha and H beta. A comparison of ejecta velocity
properties with that of existing radiation-hydrodynamical simulations indicate
that the energy of explosion lies in the range 1-2x10^51 ergs; a further
comparison of nebular phase [Oi] doublet luminosity with SNe 2004et and 1987A
indicate that the mass of progenitor star is about 14-15 M_sun. The presence of
high-velocity absorption features in the mid-to-late plateau and possibly in
early phase spectra show signs of interaction between ejecta and the
circumstellar matter; being consistent with its early-time detection at X-ray
and radio wavebands.
