.png) Lightcurve-based 3-D model ofDirikis | |
| Discovery[1] | |
|---|---|
| Discovered by | L. Chernykh |
| Discovery site | Crimean Astrophysical Obs. |
| Discovery date | 1 April 1970 |
| Designations | |
| (1805) Dirikis | |
Named after | Matiss Dirikis(astronomer)[2] |
| 1970 GD · 1942 EJ 1948 JH · 1948 JM 1950 TU1 · 1953 EL 1955 QL1 · 1959 JP 1962 WP · 1962 XC1 1964 FE | |
| main-belt · Themis[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 66.20 yr (24,178 days) |
| Aphelion | 3.4915AU |
| Perihelion | 2.7911 AU |
| 3.1413 AU | |
| Eccentricity | 0.1115 |
| 5.57yr (2,034 days) | |
| 235.42° | |
| Inclination | 2.5157° |
| 78.926° | |
| 86.389° | |
| Physical characteristics | |
| Dimensions | 22.05±1.37 km[4] 25.53 km(derived)[3] 25.70±2.7 km[5] 27.228±0.251 km[6] 28.098±0.238 km[7] |
| 23.0±0.3h[8] 23.4543 h[9] | |
| 0.0746(derived)[3] 0.0893±0.0076[7] 0.095±0.007[6] 0.1065±0.026[5] 0.145±0.019[4] | |
| S[3] | |
| 11.0[4][5][7] · 11.4[1][3] | |
1805 Dirikis, provisional designation1970 GD, is a stony Themistianasteroid from the outer region of theasteroid belt, approximately 26 kilometers in diameter.
It was discovered on 1 April 1970, by Russian astronomerLyudmila Chernykh at theCrimean Astrophysical Observatory in Nauchnyj on the Crimean peninsula.[10] It was named for Latvian astronomerMatiss Dirikis.[2]
TheS-type asteroid is a member of theThemis family,[3] a dynamical population ofouter-belt asteroids with nearly coplanarecliptical orbits. It orbits the Sun at a distance of 2.8–3.5 AU once every 5 years and 7 months (2,034 days). Its orbit has aneccentricity of 0.11 and aninclination of 3° with respect to the ecliptic.[1]
It was first observed at the FinnishTurku Observatory during WWII in 1942. The body's first used observation was its identification as1955 QL1 atGoethe Link Observatory in 1955, extending the asteroid'sobservation arc by 15 years prior to its official discovery observation.[10]
A rotationallightcurve ofDirikis was obtained from photometric observations taken by French amateur astronomerRené Roy In April 2003. It gave arotation period of 23.0 hours with a brightness variation of 0.45magnitude (U=2).[8] A 2013-published period of 23.45 hours was derived in an international study (U=n.a.).[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,Dirikis measures between 22.05 and 28.10 kilometers in diameter, and its surface has analbedo between 0.089 and 0.145.[4][5][6][7] TheCollaborative Asteroid Lightcurve Link derives an albedo of 0.075 and calculates a diameter of 25.53 kilometers with anabsolute magnitude of 11.4.[3]
Thisminor planet was named for astronomer Matiss A. Dirikis (1923–1993), who was a member of the Astronomical Observatory at theUniversity of Latvia, and chairman of the Latvian branch of theAstronomical–Geodetical Society of the U.S.S.R.. His work on the motion ofsmall Solar System bodies also contributed to the field of theoretical astronomy.[2] The officialnaming citation was published by theMinor Planet Center on 1 January 1974 (M.P.C. 3569).[11]
