luminosity kly 5102 AQpU AU TRGB Pictoris radii AUs hyperfocal Praxidike M94 NGC orbits periastron Lyrae Hipparcos parallax Mm Furlongs pc Cephei graininess colatitude Levenshtein Cepheid occulting orbiting nebula Damerau Gm 226868 lightyears metallicity orbit Cepheids bolometric M31