| Discovery[1] | |
|---|---|
| Discovered by | L. Boyer |
| Discovery site | Algiers Obs. |
| Discovery date | 3 December 1931 |
| Designations | |
| (1212) Francette | |
Named after | Francette Boyer[2] (discoverer's wife) |
| 1931 XC · 1949 HB1 1949 HZ · 1965 JB A918 KA | |
| main-belt · (outer)[1] Hilda[3][4] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 85.98 yr (31,406 days) |
| Aphelion | 4.7109AU |
| Perihelion | 3.1972 AU |
| 3.9541 AU | |
| Eccentricity | 0.1914 |
| 7.86yr (2,872 days) | |
| 282.89° | |
| 0° 7m 31.44s / day | |
| Inclination | 7.5898° |
| 149.58° | |
| 348.23° | |
| Jupiter MOID | 0.3433 AU |
| Physical characteristics | |
| Dimensions | 76.395±0.155 km[5] 82.13±3.2 km[6] 85.81±2.18 km[7] |
| 16h (poor)[8] 22.433±0.007 h[9][a] | |
| 0.037±0.002[7] 0.0400±0.003[6] 0.040±0.007[10] 0.046±0.007[5] | |
| Tholen =P[1] · P[10] SMASS =X[1][3] B–V = 0.693[1] U–B = 0.215[1] | |
| 9.54[1][3][6][7] · 9.62±0.23[11] | |
1212 Francette (provisional designation1931 XC) is a dark Hildianasteroid from the outermost regions of theasteroid belt, approximately 82 kilometers in diameter. It was discovered on 3 December 1931, by French astronomerLouis Boyer at theAlgiers Observatory in Algeria, North Africa, who named it after his wife Francette Boyer.[2][12]
Francette is the second largest member of the smallHilda family (001),[4] anasteroid family within the dynamicalHilda group,[3] that stays in anorbital resonance with the gas giantJupiter. It orbits the Sun in theoutermost asteroid belt at a distance of 3.2–4.7 AU once every 7 years and 10 months (2,872 days;semi-major axis of 3.95 AU). Its orbit has aneccentricity of 0.19 and aninclination of 8° with respect to theecliptic.[1]
The asteroid was first observed asA918 KA atSimeiz Observatory in May 1918. The body'sobservation arc begins at Algiers with its official discovery observation.[12]
In theTholen classification, Francette is a primitiveP-type asteroid.[1] In theSMASS classification it is anX-type asteroid.[1][3] TheWide-field Infrared Survey Explorer (WISE) also characterizes Francette as a dark P-type,[10] while the overallspectral type for members of the Hilda family is typically that of a carbonaceousC-type.[13]: 23
In July 2016, a rotationallightcurve of Francette was obtained from photometric observations by American astronomersBrian Warner,Robert Stephens and Dan Coley at the Center for Solar System Studies (U80–82) in California. Lightcurve analysis gave arotation period of 22.433 hours with a brightness variation of 0.13magnitude (U=2/3-), superseding a period of 16 hours, previously measured in the 1970s.[8][9][a]
According to the surveys carried out by the Infrared Astronomical SatelliteIRAS, the JapaneseAkari satellite and theNEOWISE mission of NASA's WISE telescope, Francette measures between 76.395 and 85.81 kilometers in diameter and its surface has analbedo between 0.037 and 0.046.[5][6][7][10]
TheCollaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0400 and a diameter of 82.13 kilometers based on anabsolute magnitude of 9.54.[3][6]
Thisminor planet was named by the discoverer after his wife, Francette Boyer. The official naming citation was mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 112).[2]
