GRS-1009-45 (=X-RAY NOVA VELORUM-1993) - A HYBRID SOFT-X-RAY TRANSIENT

High-time resolution photometry, performed from November 17 to Decembe r 11, 1993, on GRS 1009-45 (=X-Ray Nova Velorum 1993) reveals a V ligh t modulation with a periodicity of 0.1996 days (similar to 4(h).79). I f the nature of this modulation is similar to that of the superhumps s een in SU UMa dwarf novae during superoutbursts, then the object would have the shortest orbital period among Soft X-Ray Transients (SXTs). We estimate a lower limit for the mass of the primary of similar to 1. 6 M.. An optical secondary maximum or 'reflare' around 90 days after t he X-ray outburst is also reported. Spectroscopy during light decay co nfirms the presence of Balmer absorption lines with emission cores.