Discovery of the First in-the-Gap SU UMa-Type Dwarf Nova, NY Serpentis (=PG 1510+234)

We performed photometric monitoring and time-resolved observations of NY Ser between 1995 July 25 and 1997 March 11. NY Ser shows normal outbursts with a recurrence time of 6–9 days and superoutbursts with a recurrence time of 85–100 days in the range of 14.6–18.0 mag in the V band. The superhump period is 0.106 (± 0.001) d, which suggests that the orbital period is located near to the middle of the period gap.