The detection of a 1.4-h period in RW Ursa Minoris - candidate for shortest recorded orbital period nova

CCD photometry of the classical nova RW UMi during 10 nights in 1995 through an R filter and 14 nights in 1997 through a "clear" filter, with the l-m Wise telescope yields a periodic modulation in the light curve with the period 0.05912+/-0.00015 d and a semi amplitude of 0.025 mag. We discuss several explanations for the periodicity, and suggest that it is likely to be the orbital period of the binary system or a superhump period. RW UMi is thus a candidate for the classical nova with the shortest known orbital period.