Discovered by G. Neujmin MPC designation 952 Caia Discovered 27 October 1916 Orbits Sun | Discovery date 27 October 1916 Minor planet category main-belt · (outer) Absolute magnitude 7.51 Asteroid group Asteroid belt | |
Alternative names 1916 Σ61 · 1973 WHA908 EB · A919 GBA921 RA Similar 528 Rezia, 441 Bathilde, 824 Anastasia | ||
952 Caia, provisional designation 1916 Σ61, is a carbonaceous asteroid from the outer region of the asteroid belt, approximately 82 kilometers in diameter. It was discovered by Soviet–Russian astronomer Grigory Neujmin at the Crimean Simeiz Observatory on 27 October 1916.
The dark C-type asteroid is also classified as a P-type by NASA's Wide-field Infrared Survey Explorer (WISE). It orbits the Sun at a distance of 2.3–3.7 AU once every 5 years and 2 months (1,893 days). Its orbit has an eccentricity of 0.25 and an inclination of 10° with respect to the ecliptic. The first unused observation was made at the U.S Taunton Observatory (803) in 1908, when it was identified as 1908 EB, extending the body's observation arc by 8 years prior to its official discovery observation.
Two photoelectric light-curve observations from 1980 rendered a rotation period of 7.50 and 7.51 hours (U=2/2), while a more recent light-curve analysis in 2004 gave a period of 7000379500000000000♠3.795±0.001 hours (or half the previously determined period) with a very low brightness variation of 0.03 in magnitude (U=2), which typically indicates a nearly spheroidal shape. According to the surveys carried out by the Infrared Astronomical Satellite, IRAS, the Japanese Akari satellite, and the WISE telescope with its subsequent NEOWISE mission, the asteroid has a diameter between 81.6 and 88.8 kilometers and a low albedo in the range of 0.040 and 0.056. The Collaborative Asteroid Lightcurve Link agrees with the spaced-based observations and derives an albedo of 0.051 with a corresponding diameter of 81.5 kilometers.
The body's odd provisional designation, 1916 Σ61, was assigned at the discovering Simeiz Observatory during the First World War, when communication with the German Astronomisches Rechen-Institut, then in charge of assigning designations, was not possible over long periods of time. Instead, the observatory assigned their own, custom provisional designations containing the Greek letter sigma (Σ), in order to avoid multiple assignments. For simplicity, the letter sigma is often represented by the letter "S".
The minor planet was named after "Caia", a heroine in the historical novel Quo Vadis written by Polish journalist, novelist and laureate of the Nobel Prize in Literature in 1905, Henryk Sienkiewicz (1846–1916).