Survey typeastronomical survey Edit this on Wikidata
Observatory code691
Minor planets discovered: 130,493 [1]
see Category:Discoveries by the Spacewatch project

The Spacewatch project is an astronomical survey that specializes in the study of minor planets, including various types of asteroids and comets at Kitt Peak National Observatory near Tucson, Arizona, in the United States.

The Spacewatch Project uses four telescopes of apertures 0.9-m, 1.8-m, 2.3-m, and 4-m. These telescopes are located on Kitt Peak mountain in Arizona, and all primarily serve the purpose of locating Near-Earth Objects (NEO).[2]

It is led by astronomer Robert S. McMillan at the University of Arizona and was founded in 1980 by Tom Gehrels and McMillan. Spacewatch uses the Nicholas U. Mayall Telescope and the Steward Observatory's Bok Telescope for follow-up observations of near-Earth objects.[3][4]

The 36 inch (0.9 meter) telescope at Kitt Peak observatory has been in use by Spacewatch since 1984, and since 2000 the 72 inch Spacewatch telescope.[5] The 36 inch telescope continued in use and was further upgraded, in particular the telescopes use electronic detectors.[5]

Spacewatch’s 1.8-meter telescope is the largest in the world that is used exclusively for asteroids and comets.[6] It can find asteroids and comets anywhere from the space near Earth to regions beyond the orbit of Neptune and to do astrometry on the fainter of objects that are already known. The telescope is pointed and tracked on stars with a real time video camera at folded prime focus.

Spacewatch 1.8 meter telescope

Each year, Spacewatch observes approximately 35 radar targets, 50 Near-Earth Objects(NEO), and 100 potential rendezvous destinations. From 2013 to 2016, Spacewatch observed half of all Near-Earth Objects and Potentially Hazardous Asteroids(PHA) observed by anyone in that time. [7]


The 1.8 meter Spacewatch telescope and its building on Kitt Peak were dedicated on June 7, 1997 for the purpose of finding previously unknown asteroids and comets.[8] Since January 1 2003, Spacewatch has made ~2400 separate-night detections of Near-Earth Objects.[6]

The upgrade to the 0.9 meter was funded by NASA and the Kirsch Foundation.

The Spacewatch Project is the longest-running of all present programs of astrometry of solar system objects. [9]

Spacewatch in Action[]

Spacewatch conducted a survey that was received May 12, 2006, and accepted on November 13, 2006. This survey used data taken over 34 months by the University of Arizona’s Spacewatch Project based at Steward Observatory, Kitt Peak. Spacewatch revisited the same sky area every three to seven nights in order to track cohorts of main-belt asteroids. This survey discovered one new large Kuiper Belt Object (KBO) and detected six others. This proved that new sweeps of the sky are productive even if they have been previously examined simply due to the complexities of running large surveys over many nights and variable conditions.[10]


Asteroids are considered to be minor planets. A minor planet is an astronomical object in direct orbit around the Sun that is neither a planet nor exclusively classified as a comet. Asteroids vary in size. The largest known asteroid, Ceres, is 650 miles big.[11]

Near-Earth Objects[]

A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth.

Notable discoveries[]

Number of NEOs detected by various projects:
  All others

See also[]


  1. ^ "Minor Planet Discoverers (by number)". Minor Planet Center. 12 January 2017. Retrieved 3 February 2017.
  2. ^
  3. ^ "The Spacewatch Project". University of Arizona. 2010.
  4. ^ Solar Empire: Spacewatch Project
  5. ^ a b "Spacewatch telescope detects its first asteroids". ScienceDaily. Retrieved 18 November 2018.
  6. ^ a b McMillan, Robert S. (2006). "Spacewatch preparations for the era of deep all-sky surveys". Near Earth Objects, Our Celestial Neighbors. Proceedings of the International Astronomical Union. 2 (S236). Cambridge University Press. p. 329. doi:10.1017/S1743921307003407. ISBN 978-0521-86345-2. ISSN 1743-9213.
  7. ^
  8. ^ "1.8-m Spacewatch telescope motion control system". SPIE. Digital Library. Retrieved 18 June 2020.
  9. ^
  10. ^
  11. ^ Terrestrial and Extraterrestrial Space Dangers: Outer Space Perils, Rocket Risks and the Health Consequences of the Space Environment
  12. ^ "New outer satellite of Jupiter discovered". Minor Planet Center. Retrieved 23 July 2009.
  13. ^ "5145 Pholus (1992 AD)". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  14. ^ "9965 GNU". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  15. ^ "SDSS/SMASS asteroid taxonomy".
  16. ^ "9885 Linux". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  17. ^ "9882 Stallman". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  18. ^ "9793 Torvalds". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  19. ^ "20000 Varuna". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  20. ^ "coms06".
  21. ^ "1998 KY26". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  22. ^ "MPEC 1997-Y11: 1997 XF11". Minor Planet Center.
  23. ^ "MPEC 1999-L24: 1995 SM55, 1995 TL8, 1996 GQ21". Minor Planet Center.
  24. ^ "(136617) 1994 CC, "Beta", and "Gamma"".
  25. ^ "Spacewatch Outer Solar System Discoveries". Lunar and Planetary Laboratory. University of Arizona. Archived from the original on 29 October 2008.
  26. ^ "125P/Spacewatch".
  27. ^ "174567 Varda". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  28. ^ "2013 BS45". IAU Minor Planet Center.