In May 2010, a rotational lightcurve of Mellena was obtained from photometric observations by Robert Stephens at the Santana (646) and GMARS (G79) observatories in California. Lightcurve analysis gave a well-defined rotation period of 6.5155±0.0005 hours with a brightness variation of 0.27±0.03magnitude (U=3).[9] Subsequent observations were taken by Andrea Ferrero at the Bigmuskie Observatory (B88) in Mombercelli, Italy (U=2),[12] and Larry Owings at the Barnes Ridge Observatory in California in June 2010 (U=3),[13] as well as by Albino Carbognani Astronomical at the OAVdA Observatory (B04) in July 2010 (U=3−).[14] These observations gave a concurring period of (6.510±0.003), (6.510±0.001) and (6.515±0.001) hours with an amplitude of (0.25±0.02), (0.20±0.02) and (0.26±0.03) magnitude, respectively.[12]
Diameter and albedo
According to the surveys carried out by the Japanese Akari satellite, the Infrared Astronomical Satellite IRAS, and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), Mellena measures (18.45±0.32), (18.52±0.8) and (21.193±0.090) kilometers in diameter and its surface has an albedo of (0.058±0.002), (0.0565±0.005) and (0.057±0.022), respectively.[6][7][8] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0884 and a diameter of 18.64 kilometers based on an absolute magnitude of 11.9.[12] Alternative mean diameter measurements published by the WISE team include (15.23±3.47 km), (16.39±3.30 km), (17.77±0.46 km) and (21.953±0.153 km) with corresponding albedos of (0.12±0.17), (0.09±0.04), (0.065±0.009) and (0.0377±0.0020).[5][12]
^ abcMasiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121.