We present the complete set of ultra-violet , optical and near-infrared photometry and spectroscopy for SN 2012ca , covering the period from 6 days prior to maximum light , until 531 days after maximum .
The spectroscopic time series for SN 2012ca is essentially unchanged over 1.5 years , and appear to be dominated at all epochs by signatures of interaction with a dense circumstellar medium rather than the underlying supernova ( SN ) .
At late phases , we see a near infrared excess in flux which is possibly associated with dust formation , although without any signs of accompanying line shifts .
SN 2012ca is a member of the set of type of the ambiguous IIn/Ia-CSM SNe , the nature of which have been debated extensively in the literature .
The two leading scenarios are either a type Ia SN exploding within a dense CSM from a non-degenerate , evolved companion , or a core-collapse SN from a massive star .
While some members of the population have been unequivocally associated with type Ia SNe , in other cases the association is less certain .
While it is possible that SN 2012ca does arise from a thermonuclear SN , this would require a relatively high ( between 20 and 70 per cent ) efficiency in converting kinetic energy to optical luminosity , and a massive ( \sim 2.3 - 2.6 M _ { \odot } ) circumstellar medium .
On the basis of energetics , and the results of simple modelling , we suggest that SN 2012ca is more likely associated with a core-collapse SN .
This would imply that the observedset of similar SNe to SN 2012ca is in fact originated by two populations , and while these are drawn from physically distinct channels , they can have observationally similar properties .