| Discovery[1] | |
|---|---|
| Discovered by | E. Delporte |
| Discovery site | Uccle Obs. |
| Discovery date | 26 September 1933 |
| Designations | |
| (1293) Sonja | |
Named after | unknown[2] |
| 1933 SO | |
| Mars-crosser[1][3][4] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 83.39 yr (30,458 days) |
| Aphelion | 2.8407AU |
| Perihelion | 1.6138 AU |
| 2.2272 AU | |
| Eccentricity | 0.2754 |
| 3.32yr (1,214 days) | |
| 104.45° | |
| 0° 17m 47.4s / day | |
| Inclination | 5.3639° |
| 236.38° | |
| 99.831° | |
| Physical characteristics | |
| Dimensions | 3.65±0.45 km[5] 7.23 km(derived)[4] 7.80±0.7 km(IRAS:3)[6] |
| 2.876±0.001 h[a] 2.8768±0.0003 h[b][c] 2.87797±0.00002 h[d][e] 2.878±0.001h[7] 2.8785±0.0001 h[8] 2.879±0.001 h[f][g] 2.879±0.002 h[9] 2.881±0.002 h[h] | |
| 0.1226(derived)[4] 0.4598±0.095(IRAS:3)[6] 0.529±0.133[5] | |
| SMASS = Sq[1] · S[4] | |
| 12.00[6] · 13.50[5] · 13.6[1][4] · 13.86±0.32[10] | |
1293 Sonja, provisional designation1933 SO, is a stonyasteroid and brightMars-crosser from the innermost regions of theasteroid belt, approximately 7 kilometers in diameter. It was discovered on 26 September 1933, by Belgian astronomerEugène Delporte atUccle Observatory in Belgium.[3] Two nights later,Sonja was independently discovered by Soviet astronomerGrigory Neujmin atSimeiz on the Crimean peninsula. The origin of the asteroid's name is unknown.[2]
In theSMASS taxonomy,Sonja is classified as a Sq-type, an intermediary between the abundantS and rather rareQ-type asteroids. It orbits the Sun in theinner main-belt at a distance of 1.6–2.8 AU once every 3 years and 4 months (1,214 days). Its orbit has aneccentricity of 0.28 and aninclination of 5° with respect to theecliptic.[1]Sonja'sobservation arc begins with its official discovery observation at Uccle, as noprecoveries were taken and no prior identifications were made.[3]
Several well-defined rotationallightcurves ofSonja were obtained from photometric observations during 2003–2016.[c][g] Light-curve analysis gave a concurringrotation period of 2.876–2.879 hours with a brightness variation between 0.14 and 0.21magnitude.
In 2006, the first lightcurve was obtained byDavid Higgins (U=3),[7] followed by Federico Manzini and Vladimir Benishek (U=3/3-).[8][9] Photometric observations continued in August 2008, byPetr Pravec atOndřejov Observatory (U=3),[d][e] and in 2016, four more lightcurves were obtained byPeter Kušnirák and Petr Pravec, as well as byRobert Stephens, Daniel Klinglesmith and Isaac Aznar (U=3/3/3/3).[a][b][f][h]
According to the surveys carried out by the JapaneseAkari satellite and the Infrared Astronomical SatelliteIRAS,Sonja measures 3.65 and 7.80 kilometers in diameter, and its surface has an exceptionally highalbedo of 0.53 and 0.46, respectively.[5][6] This would makeSonja one of the brightest known Mars-crossing asteroids. However, theCollaborative Asteroid Lightcurve Link derives an albedo of 0.1226 and a diameter of 7.23 kilometers with anabsolute magnitude of 13.6.[4]
It is unknown as to whether the name "Sonja" refers to any known place, person or occurrence. It was speculated that "Sonja" could have been chosen based on the two letter of itsprovisional designation,1933 SO.[2] It is also speculated, that the name "Sonja" might have been on a list of generic German female names sent by the GermanARI to severaldiscoverers of minor planets in 1913, requesting the immediate naming of their discoveries in order to avoid confusion and possible errors (RI 1039;AN 196 and 137).[11]
Among the many thousands ofnamed minor planets,Sonja 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.[12]
