|Discovered by||J. E. Mueller|
|Discovery site||Palomar Obs.|
|Discovery date||23 August 1987|
|MPC designation||(4257) Ubasti|
(Egyptian goddess of cats)
|NEO · Apollo 
|Orbital characteristics |
|Epoch 4 September 2017 (JD 2458000.5)|
|Uncertainty parameter 0|
|Observation arc||29.02 yr (10,600 days)|
|2.11 yr (772 days)|
|0° 27m 58.32s / day|
|Earth MOID||0.1714 AU · 66.8 LD|
|Dimensions||±0.09 km 1.30
1.96 km (calculated)
|15.9 · 16.20|
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. The asteroid was named for Bastet – also known as Baast, Ubaste or Ubasti – the Egyptian goddess of cats.
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. 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.
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).
As of 2017, no rotational lightcurve of Ubasti has been obtained and its rotation period remains unknown. 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.
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, 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.
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. The official naming citation was published by the Minor Planet Center on 21 November 1991 (M.P.C. 19336). The discoverer dedicated this asteroid to her beloved companion, Pepper Cat (1974–1991).
- "JPL Small-Body Database Browser: 4257 Ubasti (1987 QA)" (2016-08-30 last obs.). Jet Propulsion Laboratory. Retrieved 15 September 2017.
- Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (4257) Ubasti. Springer Berlin Heidelberg. p. 365. ISBN 978-3-540-00238-3. Retrieved 15 September 2017.
- "4257 Ubasti (1987 QA)". Minor Planet Center. Retrieved 15 September 2017.
- Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey" (PDF). Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 15 September 2017.
- "LCDB Data for (4257) Ubasti". Asteroid Lightcurve Database (LCDB). Retrieved 15 September 2017.
- Skiff, Brian A.; Bowell, Edward; Koehn, Bruce W.; Sanborn, Jason J.; McLelland, Kyle P.; Warner, Brian D. (July 2012). "Lowell Observatory Near-Earth Asteroid Photometric Survey (NEAPS) - 2008 May through 2008 December". The Minor Planet Bulletin. 39 (3): 111–130. Bibcode:2012MPBu...39..111S. ISSN 1052-8091. Retrieved 15 September 2017.
- "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 15 September 2017.
- Asteroid Lightcurve Database (LCDB), query form (info)
- Dictionary of Minor Planet Names, Google books
- Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
- Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
- 4257 Ubasti at the JPL Small-Body Database