A NEW CATACLYSMIC VARIABLE RX J0757.0- CANDIDATE FOR THE SHORTEST PERIOD INTERMEDIATE POLAR(6306 )

A new cataclysmic variable is identified as the optical counterpart of the faint and hard X-ray source RXJ0757.0+6306 discovered during the ROSAT all-sky survey. Strong double-peaked emission lines bear evidenc e of an accretion disc via an S-wave which varies with a period of 81/-5 min. We identify this period as the orbital period of the binary s ystem. CCD photometry reveals an additional period of 8.52+/-0.15 min. which was stable over four nights. We suggest that RX 50757.0+6306 is possibly an intermediate polar, but we cannot exclude the possibility that it is a member of the SU UMa group of dwarf novae.