| Discovery[1] | |
|---|---|
| Discovered by | K. Reinmuth |
| Discovery site | Heidelberg Obs. |
| Discovery date | 9 April 1931 |
| Designations | |
| (1180) Rita | |
Named after | unknown[2] |
| 1931 GE · 1929 CM 1953 AH · 1957 UF1 A907 GG · A908 KA A916 LA | |
| main-belt · (outer)[1] · Hilda[3][4] | |
| Orbital characteristics[1] | |
| Epoch 16 February 2017 (JD 2457800.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 109.98 yr (40,172 days) |
| Aphelion | 4.6127AU |
| Perihelion | 3.3574 AU |
| 3.9851 AU | |
| Eccentricity | 0.1575 |
| 7.96yr (2,906 days) | |
| 209.15° | |
| 0° 7m 26.04s / day | |
| Inclination | 7.1985° |
| 88.336° | |
| 209.12° | |
| Jupiter MOID | 0.6111 AU |
| Physical characteristics | |
| 82.72 km(calculated)[4] 97 km[1] 97.63±2.30 km[5] | |
| 9h[6] 9.605±0.006 h[7] 12 h[8] 13.090±0.002 h[a] 14.72 h[9] 14.902 h[10] 20.496±0.005 h[b] | |
| 0.041±0.002[5] 0.044±0.008[11] 0.048[1] 0.057(assumed)[4] 0.058±0.009[12] | |
| Tholen =P[1] · P[4][11] B–V = 0.682[1] · 0.670±0.010[b] U–B = 0.216[1] V–R =0.440±0.010[b] | |
| 9.14[1][4][5] · 9.17±0.19[13] | |
1180 Rita, provisional designation1931 GE, is a dark and spheroidal Hildianasteroid from the outermost regions of theasteroid belt, approximately 97 kilometers in diameter. It was discovered on 9 April 1931, by German astronomerKarl Reinmuth at theHeidelberg Observatory in southwest Germany.[3] Any reference of its later name,Rita, is unknown.[2]
Rita belongs to the orbitalHilda group which is located in theoutermost part of the main-belt.[4] Asteroids in this dynamical group have semi-major axis between 3.7 and 4.2 AU and stay in a 3:2resonance with the gas giant Jupiter.Rita, however, is abackground asteroid and not a member of the (collisional)Hilda family (101).[14] Hildian asteroids are thought to have originated from theKuiper belt.
The asteroid orbits the Sun at a distance of 3.4–4.6 AU once every 7 years and 12 months (2,906 days). Its orbit has aneccentricity of 0.16 and aninclination of 7° with respect to theecliptic.[1]
It was first observed asA907 GG at Heidelberg in 1907. The body'sobservation arc begins at Heidelberg in 1908, when it was identified asA908 KA, approximately 23 years prior to its official discovery observation.[3]
In theTholen taxonomy,Rita is a dark and reddishP-type asteroid.[1] The P-type asteroids are some of the darkest objects in the Solar System.
Since 1983, several rotationallightcurves ofRita have been obtained from photometric observations. Lightcurve analysis gave a wide range of divergentrotation periods between 9 and 20.5 hours.[6][7][8][9][10][b] TheLight Curve Data Base adopts a period of 13.090 hours with a brightness amplitude of 0.06magnitude. Bodies with such a low brightness variation are typically of a spherical rather than elongated shape. The lightcurve was obtained in January 2017, by American astronomerBrian Warner at the Center for Solar System Studies in California (U=2).[a]
According to the surveys carried out by the JapaneseAkari satellite, and NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Rita measures 97 kilometers in diameter and its surface has analbedo between 0.041 and 0.058.[5][11][12] TheCollaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous, outer main-belt asteroids of 0.057, and calculates a diameter of 82.72 kilometers with on anabsolute magnitude of 9.14.[4]
Any reference of thisminor planet's name to a person or occurrence is unknown.[2]
Among the many thousands ofnamed minor planets,Rita is one of 120 asteroids, for which no official naming citation has been published. All of these low-numbered asteroids have numbers between164 Eva and1514 Ricouxa and were discovered between 1876 and the 1930s, predominantly by astronomersAuguste Charlois,Johann Palisa,Max Wolf andKarl Reinmuth.[15]
