RX J1039.7-0507: a new intermediate polar and probable recent nova, possessing a large reflection effect

The ROSAT source RXJ1039.7-0507, known from its optical spectrum to be a cataclysmic variable star, is shown from high-speed photometry to have an orbital period of 1.574 h. The system has a nearly sinusoidal photometric modulation with a range of 1.1 mag, which we interpret as the reflection effect caused by a very hot white dwarf primary. This suggests that a nova explosion occurred on the primary in the relatively recent past. In addition, RXJ1039.7-0507 has periodic signals at 1932.5 and 721.9 s which, with the aid of other periods present at low amplitude, we interpret as an orbital sideband and the first harmonic of the spin period of the primary. RXJ1039.7-0507 is therefore an intermediate polar with a spin period of 1444 s (24.07 min).