In September 2013, a rotational lightcurve of Manto was obtained from photometric observations by Frederick Pilcher at the Organ Mesa Observatory (G50), New Mexico, in collaboration with Eduardo Manuel Alvarez, Andrea Ferrero, Daniel Klinglesmith and Julian Oey Lightcurve analysis gave an exceptionally long rotation period of 122.30±0.01 hours with a notably high brightness amplitude of 0.80±0.05magnitude, indicative of an elongated shape (U=3).[9] With a period above 100 hours, the asteroid is a slow rotator. The result supersedes observations by Alain W. Harris from July 1981, and by astronomers at the Intermediate Palomar Transient Factory in California (U=1/1).[11]
In 2016, a modeled lightcurve gave a concurring sidereal period of 122.166±0.005 hours using data from a large collaboration of individual observers (such as above). The study also determined two spin axes of (96.0°, 30.0°) and (283.0°, 35.0°) in ecliptic coordinates (λ, β).[5][12]
Diameter and albedo
According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), Manto measures (11.87±0.16) and (13.683±0.236) kilometers in diameter and its surface has an albedo of (0.321±0.010) and (0.216±0.040), respectively.[7][8] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid of 0.20 and calculates a diameter of 13.71 kilometers based on an absolute magnitude of 11.68.[11] The WISE team also published an alternative mean-diameter measurement of (11.009±3.486 km) with a corresponding albedo of (0.305±0.181).[5][11]
^ abcUsui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)
^ abcMasiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8.
^Hanuš, J.; Ďurech, J.; Oszkiewicz, D. A.; Behrend, R.; Carry, B.; Delbo, M.; et al. (February 2016). "New and updated convex shape models of asteroids based on optical data from a large collaboration network". Astronomy and Astrophysics. 586: A108. arXiv:1510.07422. Bibcode:2016A&A...586A.108H. doi:10.1051/0004-6361/201527441. ISSN0004-6361.