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 , but the plateau is shorter and the luminosity not as constant as in other supernovae of this type . The absolute maximum magnitude , with M _ { B } = -16.23 \pm 0.16 mag , is close to the average for SN IIP . Thanks also to the strong UV flux in the early phase , SN 2012A reached a peak luminosity of about 2 \times 10 ^ { 42 } erg s ^ { -1 } , which is brighter than those of other SNe with a similar ^ { 56 } Ni mass . The latter was estimated from the luminosity in the exponential tail of the light curve and found to be M ( ^ { 56 } { Ni } ) = 0.011 \pm 0.004 M _ { \odot } , which is intermediate between standard and faint SN IIP . The spectral evolution of SN 2012A is also typical of SN IIP , from the early spectra dominated by a blue continuum and very broad ( \sim 10 ^ { 4 } km s ^ { -1 } ) 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 I D ) . The photospheric velocity is moderately low , \sim 3 \times 10 ^ { 3 } km s ^ { -1 } 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 ( \sim 15 { M _ { \odot } } ) . A candidate progenitor for SN 2012A has been identified in deep , pre-explosion K ^ { \prime } -band Gemini North ( NIRI ) images , and found to be consistent with a star with a bolometric magnitude -7.08 \pm 0.36 ( log L / L _ { \odot } = 4.73 \pm 0.14 dex ) . The magnitude of the recovered progenitor in archival images points toward a moderate-mass 10.5 _ { -2 } ^ { +4.5 } { M } _ { \odot } 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 1.8 \times 10 ^ { 13 } cm and ejecta mass of 12.5 { M _ { \odot } } . Even including the mass for the compact remnant , this appears fully consistent with the direct measurements given above .