1192 Prisma
Elongated main-belt asteroid
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1192 Prisma, provisional designation 1931 FE, is an elongated Phocaea asteroid from the inner regions of the asteroid belt, approximately 7 kilometers in diameter. It was discovered by German astronomer Friedrich Schwassmann at the Bergedorf Observatory in Hamburg on 17 March 1931.[12] The asteroid was named after the Bergedorf Spectral Catalogue, an astronomical catalog.[2]
_Prisma.png)
Modelled shape of Prisma from its lightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | A. Schwassmann |
| Discovery site | Bergedorf Obs. |
| Discovery date | 17 March 1931 |
| Designations | |
| (1192) Prisma | |
Named after | Bergedorf Spectral Catalogue (astronomical catalog)[2] |
| 1931 FE | |
| main-belt · (inner) Phocaea[3][4] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 85.77 yr (31,328 days) |
| Aphelion | 2.9762 AU |
| Perihelion | 1.7561 AU |
| 2.3661 AU | |
| Eccentricity | 0.2578 |
| 3.64 yr (1,329 days) | |
| 297.62° | |
| 0° 16m 14.88s / day | |
| Inclination | 23.902° |
| 1.3517° | |
| 131.44° | |
| Physical characteristics | |
| Dimensions | 7.22 km (calculated)[3] 7.377±0.193 km[5] 9.27±0.25 km[6] |
| 6.546±0.0170 h[7] 6.558 h[8] 6.55836±0.00005 h[9][10] | |
| 0.144±0.009[6] 0.220±0.022[5] 0.23 (assumed)[3] | |
| S[3] | |
| 12.497±0.008 (R)[7] · 12.87±0.47[11] · 12.92[1][3][5][6] | |
Classification and orbit
Prisma is a member of the Phocaea family (701), a prominent family of S-type asteroids with their largest members being 25 Phocaea and 587 Hypsipyle. There are many Mars-crossers among this family of relatively eccentric inner main-belt asteroids .[13]
The asteroid orbits the Sun at a distance of 1.8–3.0 AU once every 3 years and 8 months (1,329 days). Its orbit has an eccentricity of 0.26 and an inclination of 24° with respect to the ecliptic.[1] The body's observation arc begins at Bergedorf, one week after its official discovery observation.[12]
Physical characteristics
Rotation, shape and pole
Photometric observations of Prisma gave a well defined rotational lightcurve with a period between 6.546 and 6.558 hours and a high brightness variation of 0.85–1.16 magnitude, which strongly indicates that the body has an elongated, non-spheroidal shape (U=3/3).[7][8]
A modeled lightcurve based on optical data from a large collaboration network also found a spin axis of (133.0°, −78.0°) in ecliptic coordinates (λ, β) (Q=n.a.).[9][10]
Diameter and albedo
According to the surveys carried out by the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Prisma measures between 7.38 and 9.27 kilometers in diameter and its surface has an albedo between 0.144 and 0.220.[5][6] The Collaborative Asteroid Lightcurve Link assumes a standard albedo of 0.23 and calculates a diameter of 7.22 kilometers based on an absolute magnitude of 12.92.[3]
Naming
This minor planet was named "Prisma" (prism) in honour of the Bergedorf Spectral Catalogue (German: Bergedorfer Spektralkatalog), as prisms are one method of obtaining spectra.[2] The official naming citation was also published in Paul Herget's The Names of the Minor Planets in 1955 (H 111).[2]
