  We have identified the ROSAT all-sky survey source RX J1953.1+2115 with a
newly discovered dwarf novae (named S 10943 Vulpeculae) with a recurrence time
of 83.6 days. With the expected period of ~2.8 hrs (based on the measured
superhump period of 2.871 hrs) S 10943 Vul would be the SU Ursae Majoris star
with the second largest superhump (and orbital) period known (together with TU
Men).
