| Discovery[1] | |
|---|---|
| Discovered by | H. van Gent |
| Discovery site | Johannesburg Obs. (Leiden Southern Station) |
| Discovery date | 16 September 1930 |
| Designations | |
| (1689) Floris-Jan | |
Named after | Floris-Jan van der Meulen (Contest Winner)[2] |
| 1930 SO · 1926 PG 1928 DN · 1934 VV 1943 AC · 1949 OF 1949 ON1 · 1949 OY 1951 CW · 1966 BP | |
| main-belt · (inner)[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 89.19 yr (32,577 days) |
| Aphelion | 2.9545AU |
| Perihelion | 1.9461 AU |
| 2.4503 AU | |
| Eccentricity | 0.2058 |
| 3.84yr (1,401 days) | |
| 218.98° | |
| 0° 15m 25.2s / day | |
| Inclination | 6.3757° |
| 123.19° | |
| 265.10° | |
| Physical characteristics | |
| Dimensions | 13.743±1.905 km[4] 13.99±0.23 km[5] 16.122±4.950 km[6] 16.21 km(taken)[3] 16.213 km[7] |
| 0.083 h(fragm.)[8] 144.85±0.20 h[9] 145h[10] | |
| 0.1271±0.0508[6] 0.1353[7] 0.175±0.050[4] 0.184±0.007[5] | |
| S[3] B–V = 0.685[1] U–B = 0.265[1] | |
| 11.74±0.05[3][7][9] · 11.79±0.19[11] · 11.82[1][4][5][6] | |
1689 Floris-Jan, provisional designation1930 SO, is a stonyasteroid and aslow rotator from the inner regions of theasteroid belt, approximately 16 kilometers in diameter. Discovered byHendrik van Gent in 1930, it was named after a contest winner of an exhibition atLeiden Observatory.
The asteroid was discovered on 16 September 1930, by Dutch astronomerHendrik van Gent at the Leiden Southern Station, annex to theJohannesburg Observatory in South Africa.[12] It was independently discovered by Soviet astronomer Evgenii Skvortsov at the Crimean Simeiz Observatory five days later.[2]
Floris-Jan orbits the Sun in theinner main-belt at a distance of 1.9–3.0 AU once every 3 years and 10 months (1,401 days). Its orbit has aneccentricity of 0.21 and aninclination of 6° with respect to theecliptic.[1] First identified as1926 PG atSimeiz Observatory in 1926, the body'sobservation arc begins 3 days after its official discovery observation at Johannesburg in 1930.[12]
In the 1980s, photometriclightcurve observations already revealed thatFloris-Jan is avery slow rotator with arotation period of 145 hours and a brightness variation of 0.4magnitude (U=3).[10] At the time, this six-day period was a new record among all minor planets with a known rotation period, and it was assumed, thatFloris-Jan might also be a tumbling asteroid with a non-principal axis rotation.[3][9]
According to the surveys carried out by the JapaneseAkari satellite and NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Floris-Jan measures between 13.74 and 16.12 kilometers in diameter, and its surface has analbedo between 0.127 and 0.184.[4][5][6] TheCollaborative Asteroid Lightcurve Link agrees withPetr 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.[3]
Thisminor planet was named for Floris-Jan van der Meulen, the 5,000th visitor to a 14-day astronomical exhibition at theLeiden Observatory.[2] The officialnaming citation was published by theMinor Planet Center on 1 March 1973 (M.P.C. 3470).[13]
