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 U.S Palomar Observatory in California [REF].
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.