Periodic modulation of the optical counterpart of the X-ray pulsator 1WGA J1958.2+3232. A new intermediate polar

Time-resolved observations of a 6' x 6' field, containing the position erro r boxes of the X-ray source 1WGA J1958.2+3232, were performed in June 1999 with the 91 cm Catania telescope, equipped with a Photon Counting Intensifi ed CCD, The star recently proposed as the optical counterpart of the 1WGA J 1958.2+3232, exhibited a strong optical modulation with a period compatible with that seen in X-ray (similar to 12 min). The optical modulation was de tected again in September and October 1999. These results confirm the ident ification of the optical counterpart and support the classification of 1WGA J1958.2+3232 as a cataclysmic variable, possibly an Intermediate Polar. Mo dulation at a period twice as large was also found in one observation run, thus suggesting that the true spin period of the White Dwarf could be 24 mi n rather than 12 min, which would make 1WGA J1958.2+3232 appears to be, amo ng the IPs, the slowest rotator which exhibits double peaked spin profile.