|Discovered by||C. van Houten
I. van Houten
|Discovery site||Palomar Obs.|
|Discovery date||24 September 1960|
|MPC designation||(5011) Ptah|
|6743 P-L · 1983 TF2|
|Apollo · NEO · PHA 
|Orbital characteristics |
|Epoch 4 September 2017 (JD 2458000.5)|
|Uncertainty parameter 0|
|Observation arc||55.90 yr (20,419 days)|
|2.09 yr (764 days)|
|0° 28m 15.96s / day|
|Earth MOID||0.0256 AU · 10 LD|
|Dimensions||1.56 km (calculated)|
5011 Ptah (//), provisional designation 6743 P-L, is an eccentric, rare-type asteroid, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, and measures approximately 1.6 kilometers in diameter. Discovered during the Palomar–Leiden survey in 1960, it was later named after the Ancient Egyptian deity 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. 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.
Classification and orbit
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. As no precoveries were taken, the asteroid's observation arc begins with its official discovery observation at Palomar.
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 Gm. The next time will be in 2027 at 28.6 Gm. Due to its high eccentricity, Ptah is also a Mars-crosser.
The Collaborative Asteroid Lightcurve Link assumes an standard albedo for stony asteroids of 0.20, and calculates a mean diameter of 1.6 kilometers using an absolute magnitude of 16.4. As of 2017, no rotational lightcurves have been obtained of Ptah, and its period and shape, as well as its spectral type remains unknown.
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. The approved naming citation was published by the Minor Planet Center on 16 May 1992 (M.P.C. 20163).
- "JPL Small-Body Database Browser: 5011 Ptah (6743 P-L)" (2016-08-20 last obs.). Jet Propulsion Laboratory. Retrieved 4 July 2017.
- Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (5011) Ptah. Springer Berlin Heidelberg. p. 431. ISBN 978-3-540-00238-3. Retrieved 11 August 2016.
- "5011 Ptah (6743 P-L)". Minor Planet Center. Retrieved 11 August 2016.
- "LCDB Data for (5011) Ptah". Asteroid Lightcurve Database (LCDB). Retrieved 11 August 2016.
- Thomas, Cristina A.; Emery, Joshua P.; Trilling, David E.; Delbó, Marco; Hora, Joseph L.; Mueller, Michael (January 2014). "Physical characterization of Warm Spitzer-observed near-Earth objects". Icarus. 228: 217–246. Bibcode:2014Icar..228..217T. arXiv: . doi:10.1016/j.icarus.2013.10.004. Retrieved 11 August 2016.
- "Minor Planet Discoverers". Minor Planet Center. 20 June 2016. Retrieved 10 August 2016.
- "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 11 August 2016.
- 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 (5001)-(10000) – Minor Planet Center
- 5011 Ptah at the JPL Small-Body Database