A near-infrared survey of old novae - I. The discovery of a candidate recurrent nova.

We report on a near-infrared survey of old novae in an attempt to discover previously unidentified members of the RS Oph family of recurrent novae. An RS Oph-type system contains a red giant, and is easily identified using infrared photometry. Two objects in our survey have infrared colors and luminosities that suggest that they may be recurrent novae: V723 Sco and AR Cir. We use a model of the Galaxy to rule out the possibility of source confusion in either case. The light curve of the 1952 outburst of V723 Sco was very similar to those of the other members of the RS Oph group of recurrent novae, and we conclude that it is a previously unidentified member of this family. The light curve of the 1906 outburst of AR Cir, however, more closely resembles those of the outbursts of symbiotic stars, and we classify it as such.