| Discovery[1] | |
|---|---|
| Discovered by | Y. Väisälä |
| Discovery site | Turku Obs. |
| Discovery date | 18 September 1939 |
| Designations | |
| (1524) Joensuu | |
Named after | Joensuu(Finnish town)[2] |
| 1939 SB · 1931 EL 1933 QO · 1936 DG 1958 DH1 | |
| main-belt · (outer)[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 85.95 yr (31,395 days) |
| Aphelion | 3.4881AU |
| Perihelion | 2.7300 AU |
| 3.1090 AU | |
| Eccentricity | 0.1219 |
| 5.48yr (2,002 days) | |
| 88.699° | |
| 0° 10m 47.28s / day | |
| Inclination | 12.687° |
| 347.72° | |
| 2.7611° | |
| Physical characteristics | |
| Dimensions | 39.37±12.22 km[4] 42.79±1.1 km[5] 42.83 km(derived)[3] 44.87±0.78 km[6] 45.056±0.291 km[7] 49.394±0.502 km[8] |
| 9.276±0.007h[9] | |
| 0.0347±0.0053[8] 0.043±0.002[6] 0.0462±0.002[5] 0.050±0.008[7] 0.0505(derived)[3] 0.064±0.007[10] 0.07±0.05[4] | |
| C[3] | |
| 10.56±0.50[11] · 10.60[7] · 10.7[1][3] · 10.78[4] · 10.8[5][6][8] | |
1524 Joensuu (provisional designation1939 SB) is a carbonaceousasteroid from the outer region of theasteroid belt, approximately 42 kilometers in diameter. It was discovered on 18 September 1939, by Finnish astronomerYrjö Väisälä atTurku Observatory in Southwest Finland, and named for the town ofJoensuu.[12]
Joensuu is a darkC-type asteroid, that orbits the Sun in theouter main-belt at a distance of 2.7–3.5 AU once every 5 years and 6 months (2,002 days). Its orbit has aneccentricity of 0.12 and aninclination of 13° with respect to theecliptic.[1] In 1931, Joensuu was first identified as1931 EL atHeidelberg Observatory, extending the body'sobservation arc by 8 years prior to its official discovery observation.[12]
In October 2005, a rotationallightcurve of Joensuu was obtained from photometric observations by French amateur astronomerLaurent Bernasconi. It gave a well-definedrotation period of 9.276 hours with a change in brightness of 0.33magnitude (U=3).[9]
According to the surveys carried out by the Infrared Astronomical SatelliteIRAS, the JapaneseAkari satellite, and NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission, Joensuu measures between 39.37 and 49.39 kilometers in diameter, and its surface has analbedo between 0.034 and 0.07.[4][5][6][7][8] TheCollaborative Asteroid Lightcurve Link derives an albedo of 0.0505 and a diameter of 42.83 kilometers using anabsolute magnitude of 10.7.[3]
Thisminor planet was named for the Finnish townJoensuu, where the discoverer received his early schooling. It is located inNorth Karelia, near the Russian border.[2] The officialnaming citation was published by theMinor Planet Center on 20 February 1976 (M.P.C. 3929).[13]
