SN 2013ej - A type IIL supernova with weak signs of interaction
  We present optical photometric and spectroscopic observations of supernova
2013ej. It is one of the brightest type II supernovae exploded in a nearby
($\sim 10$ Mpc) galaxy NGC 628. The light curve characteristics are similar to
type II SNe, but with a relatively shorter ($ \sim85 $ day) and steeper ($
\sim1.7 $ mag (100 d)$^{-1} $ in V) plateau phase. The SN shows a large drop of
2.4 mag in V band brightness during plateau to nebular transition. The absolute
ultraviolet (UV) light curves are identical to SN 2012aw, showing a similar UV
plateau trend extending up to 85 days. The radioactive $^{56}$Ni mass estimated
from the tail luminosity is $ 0.02 $M$_{\odot}$ which is significantly lower
than typical type IIP SNe. The characteristics of spectral features and
evolution of line velocities indicate that SN 2013ej is a type II event.
However, light curve characteristics and some spectroscopic features provide
strong support in classifying it as a type IIL event. A detailed SYNOW
modelling of spectra indicates the presence of some high velocity components in
H$\alpha$ and H$\beta$ profiles, implying possible ejecta-CSM interaction. The
nebular phase spectrum shows an unusual notch in the H$\alpha$ emission which
may indicate bipolar distribution of $^{56}$Ni. Modelling of the bolometric
light curve yields a progenitor mass of $ \sim14 $M$_{\odot}$ and a radius of $
\sim450 $R$_{\odot}$, with a total explosion energy of $ \sim2.3\times10^{51} $
erg.
