4257 Ubasti
Near-Earth asteroid
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4257 Ubasti, provisional designation 1987 QA, is a stony asteroid, classified as near-Earth object of the Apollo group and as Mars-crosser, approximately 1.5 kilometers in diameter. It was discovered by American astronomer Jean Mueller at the Palomar Observatory in California on 23 August 1987.[3] The asteroid was named for Bastet – also known as Baast, Ubaste or Ubasti – the Egyptian goddess of cats.[2]
| Discovery[1] | |
|---|---|
| Discovered by | J. E. Mueller |
| Discovery site | Palomar Obs. |
| Discovery date | 23 August 1987 |
| Designations | |
| (4257) Ubasti | |
Named after | Bastet[2] (Egyptian goddess of cats) |
| 1987 QA | |
| NEO · Apollo[1][3] Mars-crosser | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 29.02 yr (10,600 days) |
| Aphelion | 2.4183 AU |
| Perihelion | 0.8759 AU |
| 1.6471 AU | |
| Eccentricity | 0.4682 |
| 2.11 yr (772 days) | |
| 28.670° | |
| 0° 27m 58.32s / day | |
| Inclination | 40.716° |
| 169.22° | |
| 278.92° | |
| Earth MOID | 0.1714 AU · 66.8 LD |
| Physical characteristics | |
| Dimensions | 1.30±0.09 km[4] 1.96 km (calculated)[5] |
| 0.20 (assumed)[5] 0.376±0.053[4] | |
| S[5] | |
| 15.9[1][5] · 16.20[4] | |
Orbit and classification
Ubasti orbits the Sun at a distance of 0.9–2.4 AU once every 2 years and 1 month (772 days). Its orbit has an eccentricity of 0.47 and an inclination of 41° with respect to the ecliptic.[1] Due to its high eccentricity, Ubasti is also a Mars-crossing asteroid. The body's observation arc begins with its official discovery observation, as no precoveries were taken and no prior identification had been made.[3]
Close approaches
As a near-Earth object, Ubasti has a low Earth minimum orbital intersection distance of 0.1714 AU (25,600,000 km), which corresponds to 66.8 lunar distances (LD). This distance, however, is too large to make it a potentially hazardous asteroid (0.05 AU; less than 20 LD).[1]
Physical characteristics
Ubasti is an assumed stony S-type asteroid.[5]
Rotation period
As of 2017, no rotational lightcurve of Ubasti has been obtained and its rotation period remains unknown.[5] However, the Lowell Observatory Near-Earth Asteroid Photometric Survey has measured the body's brightness variation caused by its rotation, which gave a maximum of 0.36 magnitude. This indicates that the body has a somewhat non-spherical shape.[6]
Diameter and albedo
According to the survey carried out by the Japanese Akari satellite, Ubasti measures 1.30 kilometers in diameter and its surface has an albedo of 0.376,[4] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 1.96 kilometers based on an absolute magnitude of 15.9.[5]
Naming
This minor planet was named after Egyptian goddesses Bastet, who was originally the goddess of warfare, equated with the lioness war goddess, but later transformed into a major protector deity represented as a cat.[2] The official naming citation was published by the Minor Planet Center on 21 November 1991 (M.P.C. 19336).[7] The discoverer dedicated this asteroid to her beloved companion, Pepper Cat (1974–1991).[2]
