| Discovery[1] | |
|---|---|
| Discovered by | Y. Väisälä |
| Discovery site | Turku Observatory |
| Discovery date | 18 September 1939 |
| Designations | |
| (1536) Pielinen | |
Named after | Pielinen(lake)[2] |
| 1939 SE · 1929 RZ 1931 ED · 1934 CW 1939 TP · 1939 UK 1952 RW · A903 SF A916 RA | |
| main-belt · Flora[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 113.68 yr (41,521 days) |
| Aphelion | 2.6342AU |
| Perihelion | 1.7736 AU |
| 2.2039 AU | |
| Eccentricity | 0.1953 |
| 3.27yr (1,195 days) | |
| 295.85° | |
| 0° 18m 4.32s / day | |
| Inclination | 1.5344° |
| 195.69° | |
| 170.76° | |
| Physical characteristics | |
| Dimensions | 7.38±1.62 km[4] 7.82 km(calculated)[3] 7.934±0.037 km[5] 7.975±0.109 km[6] |
| 66.1±0.1 h[7] 66.22 h[a] 66.34±0.02h[b] 67.43±0.06 h[8] | |
| 0.24(assumed)[3] 0.253±0.017[6] 0.2557±0.0662[5] 0.30±0.21[4] | |
| S[3][9] | |
| 12.57±0.52[9] · 12.6[5] · 12.7[1][3][4] | |
1536 Pielinen (provisional designation1939 SE) is a stony Florianasteroid from the inner regions of theasteroid belt, approximately 7.8 kilometers in diameter. It was discovered on 18 September 1939, by Finnish astronomerYrjö Väisälä atTurku Observatory, Southwest Finland.[10] It was later named for Finnish lakePielinen.[2]
Pielinen is a member of theFlora family, a large group of stonyS-type asteroids. It orbits the Sun in theinner main-belt at a distance of 1.8–2.6 AU once every 3 years and 3 months (1,195 days). Its orbit has aneccentricity of 0.20 and aninclination of 2° with respect to theecliptic.[1]Pielinen was first identified asA903 SF atHeidelberg in 1903, extending the body'sobservation arc by 36 years prior to its official discovery observation.[10]
From September to November 2011, four rotationallightcurves of Pielinen were obtained from photometric observations. One lightcurve analysis gave a rotation period of 66.2 hours,[c] which is significantly longer than for most minor planets, that spin every 2 to 20 hours around their axis. However,slow rotators have periods typically above 100 hours. Photometric observations were taken byPetr Pravec (66.22 hours, Δ0.85 mag,U=3),[a]Robert D. Stephens (66.34 hours, Δ0.80mag,U=3-),[b] Giovanni Casalnuovo (66.1 hours, Δ0.75 mag,U=2+),[7] andSilvano Casulli (67.43 hours, Δ0.81 mag,U=2).[8]
According to the space-based survey carried out by NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission, Pielinen measures between 7.38 and 7.975 kilometers in diameter and its surface has analbedo between 0.253 and 0.30.[4][5][6] TheCollaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from8 Flora, the largest member and namesake of this family – and calculates a diameter of 7.82 kilometers, with anabsolute magnitude of 12.7.[3]
Thisminor planet is named afterPielinen, Finland's fourth largest lake inFinnish Karelia. TheKoli National Park is located on its western shores.[2] The officialnaming citation was published by theMinor Planet Center on 20 February 1976 (M.P.C. 3930).[11]
