We report the discovery of 1RXS J173006.4+033813, a polar cataclysmic variable with a period of 120.21 minutes. The white dwarf primary has a magnetic field of B=42^+6^-5_MG and the secondary is an M3 dwarf. The system shows highly symmetric double-peaked photometric modulation in the active state as well as in quiescence. These arise from a combination of cyclotron beaming and ellipsoidal modulation. The projected orbital velocity of the secondary is K_2=390+/-4km/s. We place an upper limit of 830+/-65pc on the distance.
Cone search capability for table J/ApJ/721/412/table2 (Photometry of reference stars for 1RXS J173006.4+033813)