5011 Ptah

Ptah was discovered on 24 September 1960, by Dutch astronomers Ingrid and Cornelis van Houten at Leiden, on photographic plates taken by Dutch–American astronomer Tom Gehrels at the Palomar Observatory in California.^[4] On the same night, the trio of astronomers also discovered the minor planets 1912 Anubis, 1923 Osiris and 1924 Horus, which were also named after Ancient Egyptian deities.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.^[7]

This minor planet was named for the Egyptian creator deity Ptah. In Egyptian mythology, he is the creator of the universe and god of craftsmen and architects. The deity was generally represented in a human form with a sceptre and an ankh.^[3] The approved naming citation was published by the Minor Planet Center on 16 May 1992 (M.P.C. 20163).^[8]

Ptah orbits the Sun at a distance of 0.8–2.5 AU once every 2 years and 1 month (764 days). Its orbit has an eccentricity of 0.50 and an inclination of 7° with respect to the ecliptic.^[1] As no precoveries were taken, the asteroid's observation arc begins with its official discovery observation at Palomar.^[4]

The potentially hazardous asteroid has a minimum orbit intersection distance with Earth of 0.0256 AU (3,830,000 km) or 10 lunar distances. It passes within that distance of Earth 15 times between 1900 and 2100, most recently on 21 January 2007, at 29.6 million km. The next time will be in 2027 at 28.6 million km.^[1] Due to its high eccentricity, Ptah is also a Mars-crosser.