Discovered by H. van Gent MPC designation 1689 Floris-Jan Discovered 16 September 1930 Orbits Sun Discovery site Union Observatory | Discovery date 16 September 1930 Minor planet category main-belt · (inner) Absolute magnitude 11.82 Discoverer Hendrik van Gent Asteroid group Asteroid belt | |
Named after Floris-Jan van der Meulen
(Contest Winner) Alternative names 1930 SO · 1926 PG
1928 DN · 1934 VV
1943 AC · 1949 OF
1949 ON1 · 1949 OY
1951 CW · 1966 BP People also search for Sun, 2945 Zanstra, 1383 Limburgia | ||
1689 Floris-Jan, provisional designation 1930 SO, is a stony asteroid and a slow rotator from the inner regions of the asteroid belt, approximately 16 kilometers in diameter. It was discovered on 16 September 1930, by Dutch astronomer Hendrik van Gent at the Leiden Southern Station, annex to the Johannesburg Observatory in South Africa. It was independently discovered by Soviet astronomer Evgenii Skvortsov at the Crimean Simeiz Observatory five days later.
Floris-Jan orbits the Sun at a distance of 1.9–3.0 AU once every 3 years and 10 months (1,402 days). Its orbit has an eccentricity of 0.21 and an inclination of 6° with respect to the ecliptic. First identified as 1926 PG at Simeiz Observatory in 1926, the body's observation arc begins 3 days after its official discovery observation at Johannesburg in 1930.
In the 1980s, photometric light-curve observations already revealed that Floris-Jan is a very slow rotator with a rotation period of 145 hours and a brightness variation of 0.4 magnitude (U=3). At the time, this six-day period was a new record among all minor planets with a known rotation period, and it was assumed, that Floris-Jan might also be a tumbling asteroid with a non-principal axis rotation.
According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Floris-Jan measures between 13.74 and 16.12 kilometers in diameter, and its surface has an albedo between 0.127 and 0.184. The Collaborative Asteroid Lightcurve Link agrees with Petr Pravec's revised WISE-data, that is an albedo of 0.135 and a diameter of 16.21 kilometers based on an absolute magnitude of 11.74.
This minor planet was named for Floris-Jan van der Meulen, the 5,000th visitor to a 14-day astronomical exhibition at the Leiden Observatory. Naming citation was published before November 1977 (M.P.C. 3470).