309 Fraternitas is a typical Main beltasteroid.[2] It was discovered by Johann Palisa on 6 April 1891 in Vienna. The asteroid name is Latin for 'fraternity'; it was so named in order to commemorate the 25th anniversary of the Maturitätsprüfung Fraternity.[3]
This minor planet is orbiting the Sun at a distance of 2.665 AU with an orbital eccentricity (ovalness) of 0.115 and a period of 4.35 yr. The orbital plane is inclined at an angle of 3.72° of the ecliptic. Analysis of the asymmetric bimodal light curve of the asteroid from photometric data collected during 2014 provide a rotation period of 22.398±0.001 h with a brightness variation of 0.12±0.01 in magnitude.[4]
^Robinson, L. E. (June 2002), "Photometry of Five Difficult Asteroids: 309 Fraternitas, 366 Vincentina 421 Zahringia, 578 Happelia, 959 Anne", The Minor Planet Bulletin, 29: 30–31, Bibcode:2002MPBu...29...30R.
^Pilcher, Frederick (January 2015), "Rotation Period Determinations for 275 Sapientia, 309 Fraternitas, and 924 Toni", Bulletin of the Minor Planets Section of the Association of Lunar and Planetary Observers, vol. 42, no. 1, pp. 38–39, Bibcode:2015MPBu...42...38P.
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