We have obtained photometry of stars in NGC 2264 with several combinations of Hα filters and continuum filters. The main purpose of these observations was to determine the best filter combination for selecting low ma!,s member stars in their Pre-Main Sequence (PMS) stage using Hα photometry. A narrow band Hα filter (Δ⋋ = l0Å) with any combination of continuum filters showed the highest resolution in the Hα photometry.

• LEE KANG HWAN(Department of Astronomy, Seoul National University)
• SUNG HWANKYUNG(Department of Astronomy, Seoul National University/Research Institute of Basic Sciences, Seoul National University)