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]

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]

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]

Ubasti is an assumed stony S-type asteroid. ^[5]

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]

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]

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]

• Asteroid Lightcurve Database (LCDB), query form ( info Archived 16 December 2017 at the Wayback Machine)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• 4257 Ubasti at NeoDyS-2, Near Earth Objects—Dynamic Site
  • Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
• 4257 Ubasti at ESA– space situational awareness
  • Ephemerides · Observations · Orbit · Physical properties · Summary
• 4257 Ubasti at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters