  We present the one-year long observing campaign of SN 2012A which exploded in
the nearby (9.8 Mpc) irregular galaxy NGC 3239. The photometric evolution is
that of a normal type IIP supernova. The absolute maximum magnitude, with MB =
-16.23 +- 0.16 mag. SN2012A reached a peak luminosity of about 2X10**42 erg/s,
which is brighter than those of other SNe with a similar 56Ni mass. The latter
was estimated from the luminosity in the exponential tail of the light curve
and found to be M(56Ni) = 0.011 +-0.004 Msun. The spectral evolution of SN
2012A is also typical of SN IIP, from the early spectra dominated by a blue
continuum and very broad (~10**4 km/s) Balmer lines, to the late-photospheric
spectra characterized by prominent P-Cygni features of metal lines (Fe II, Sc
II, Ba II, Ti II, Ca II, Na ID). The photospheric velocity is moderately low,
~3X10**3 km/s at 50 days, for the low optical depth metal lines. The nebular
spectrum obtained 394 days after the shock breakout shows the typical features
of SNe IIP and the strength of the [O I] doublet suggests a progenitor of
intermediate mass, similar to SN 2004et (~15 Msun). A candidate progenitor for
SN 2012A has been identified in deep, pre-explosion K'-band Gemini North (NIRI)
images, and found to be consistent with a star with a bolometric magnitude
-7.08+-0.36 (log L/Lsun = 4.73 +- 0.14$ dex). The magnitude of the recovered
progenitor in archival images points toward a moderate-mass 10.5 (-2/+4.5) Msun
star as the precursor of SN 2012A. The explosion parameters and progenitor mass
were also estimated by means of a hydrodynamical model, fitting the bolometric
light curve, the velocity and the temperature evolution. We found a best fit
for a kinetic energy of 0.48 foe, an initial radius of 1.8X10**13 cm and ejecta
mass of 12.5 Msun.
