| Discovery[1] | |
|---|---|
| Discovered by | S. Arend |
| Discovery site | Uccle Obs. |
| Discovery date | 27 October 1949 |
| Designations | |
| (1573) Väisälä | |
Named after | Yrjö Väisälä(astronomer)[2] |
| 1949 UA | |
| main-belt · Phocaea[3][4] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 67.51 yr (24,659 days) |
| Aphelion | 2.9192AU |
| Perihelion | 1.8243 AU |
| 2.3717 AU | |
| Eccentricity | 0.2308 |
| 3.65yr (1,334 days) | |
| 225.00° | |
| 0° 16m 11.28s / day | |
| Inclination | 24.553° |
| 202.38° | |
| 173.91° | |
| Physical characteristics | |
| Dimensions | 8.43±1.90 km[5] 9.083±0.055 km[6] 9.146±0.066 km[7] 9.77 km(IRAS:2)[8] |
| 252h[a] | |
| 0.2226(IRAS:2)[8] 0.25±0.12[5] 0.2818±0.0319[6] 0.284±0.045[9] | |
| S[3] | |
| 12.2[6] · 12.30[1][3] · 12.47[5] · 12.84±0.50[10] | |
1573 Väisälä, provisional designation1949 UA, is a stony Phocaeaasteroid,slow rotator and suspected tumbler from the inner regions of theasteroid belt, approximately 9 kilometers in diameter. It was discovered on 27 October 1949, by Belgian astronomerSylvain Arend at theRoyal Observatory of Belgium in Uccle, Belgium.[11] It was named for Finnish astronomerYrjö Väisälä.[2]
The stonyS-type asteroid is a member of thePhocaea family (701), a group of asteroids with similar orbital characteristics.[4] It orbits the Sun at a distance of 1.8–2.9 AU once every 3 years and 8 months (1,334 days). Its orbit has aneccentricity of 0.23 and aninclination of 25° with respect to theecliptic.[1]Väisälä'sobservation arc begins on the night following its official discovery observation at Uccle, as noprecoveries were taken and no prior identifications were made.[11]
In September 2011, a rotationallightcurve ofVäisälä was obtained from photometric observations made by Czech astronomerPetr Pravec atOndřejov Observatory.[b] Its analysis gave arotation period of 252 hours with a brightness variation of 0.76magnitude (U=2).[a] This makesVäisälä one of theTop 200 slow rotators known to exist. The body is also suspected to be in a non-principal axis rotation (NPAR), colloquially called as "tumbling". As of 2017, no follow-up observations have been made of these provisional results.[3]
According to the space-based surveys carried out by the Infrared Astronomical SatelliteIRAS, and NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Väisälä measures between 8.43 and 9.77 kilometers in diameter, and its surface has analbedo between 0.222 and 0.284.[5][6][7][8] TheCollaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.2226 and a diameter of 9.77 kilometers using on anabsolute magnitude of 12.30.[3]
Thisminor planet was named after Finnish astronomer,Yrjö Väisälä (1891–1971), a prolificdiscoverer of minor planets during the late 1930s and early 1940s.[2] In addition, a second minor planet,2804 Yrjö, was named in his honor by pioneering Finnish female astronomerLiisi Oterma, and the lunar craterVäisälä also bears his name. The officialnaming citation was published by theMinor Planet Center on 31 January 1962 (M.P.C. 2116).[12]
