Coordinates: 31°57′44″N 111°36′01″W / 31.96219°N 111.60034°W / 31.96219; -111.60034
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Spacewatch 1.8-meter telescope
Coordinates31°57′44″N 111°36′01″W / 31.96219°N 111.60034°W / 31.96219; -111.60034 Edit this at Wikidata
Observatory code691
Minor planets discovered: 169,873 [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 University of Arizona telescopes on Kitt Peak near Tucson, Arizona, in the United States. The Spacewatch Project has been active longer than any other similar currently active programs.[2]

Spacewatch was founded in 1980 by Tom Gehrels and Robert S. McMillan, and is currently led by astronomer Melissa Brucker at the University of Arizona. Spacewatch uses several telescopes on Kitt Peak for follow-up observations of near-Earth objects.[3]

The Spacewatch Project uses three telescopes of apertures 0.9-m, 1.8-m, and 2.3-m. These telescopes are located on Kitt Peak mountain in Arizona, and the first two are dedicated to the purpose of locating Near-Earth Objects (NEOs).[4]

The 36 inch (0.9 meter) telescope on Kitt Peak has been in use by Spacewatch since 1984, and since 2000 the 72 inch (1.8 meter) 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 on stars and tracked with a real time video-rate camera at folded prime focus.

Spacewatch was the first to use CCDs to survey the sky for comets and asteroids. When added, they permitted faster coverage of the sky than the pre-2002 system.[7]

Each year, Spacewatch observes approximately 35 radar targets, 50 near-Earth objects, and 100 potential spacecraft rendezvous destinations. From 2013 to 2016, Spacewatch observed half of all NEOs and potentially hazardous asteroids (PHAs) observed by anyone in that time.[4] As of 2022, Spacewatch had discovered over 179,000 minor planets numbered by the Minor Planet Center.[8]


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.[9] Since January 1 2003, Spacewatch has made ~2400 separate-night detections of Near-Earth Objects.[6]

There was an upgrade to the 0.9 meter which 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.[4]

Spacewatch in Action[edit]

Spacewatch conducted a survey that was proposed 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]

Notable discoveries[edit]

Number of NEOs detected by various projects:
  All others

See also[edit]


  1. ^ "Minor Planet Discoverers (by number)". Minor Planet Center. 12 January 2017. Retrieved 3 February 2017.
  2. ^ McMillan, Robert (2001). "The Spacewatch Project" (PDF). National Space Society. Retrieved 6 June 2022.
  3. ^ "The Spacewatch Project". University of Arizona. 2010.
  4. ^ a b c McMillan, Robert S.; Larsen, Jeffrey A.; Bressi, Terrence H.; Scotti, James V.; Mastaler, Ronald A.; Tubbiolo, Andrew F. (August 2015). "Spacewatch Astrometry and Photometry of Near-Earth Objects". Proceedings of the International Astronomical Union. 10 (S318): 317–318. doi:10.1017/S1743921315006766. S2CID 125071840.
  5. ^ a b "Spacewatch telescope detects its first asteroids". ScienceDaily. Retrieved 18 November 2018.
  6. ^ a b McMillan, Robert S. (2007). "Spacewatch preparations for the era of deep all-sky surveys". Proceedings of the International Astronomical Union. Symposium S236: Near Earth Objects, our Celestial Neighbors: Opportunity and Risk, August 2006. Vol. 2. Cambridge University Press. p. 329. doi:10.1017/S1743921307003407. ISBN 978-0-521-86345-2. ISSN 1743-9213.
  7. ^ "Home SPACEWATCH®". The University of Arizona. Retrieved 3 November 2021.
  8. ^ "IAU Minor Planet Center".
  9. ^ Perry, Marcus L.; Bressi, Terrence; McMillan, Robert S.; Tubbiolo, Andrew; Barr, Lawrence D. (26 May 1998). Lewis, Hilton (ed.). "1.8-m Spacewatch telescope motion control system". Telescope Control Systems III. 3351: 450–465. Bibcode:1998SPIE.3351..450P. doi:10.1117/12.308809. S2CID 62230373.
  10. ^ Larsen, Jeffrey A.; Roe, Eric S.; Albert, C. Elise; Descour, Anne S.; McMillan, Robert S.; Gleason, Arianna E.; Jedicke, Robert; Block, Miwa; Bressi, Terrence H.; Cochran, Kim C.; Gehrels, Tom; Montani, Joseph L.; Perry, Marcus L.; Read, Michael T.; Scotti, James V.; Tubbiolo, Andrew F. (1 April 2007). "The Search for Distant Objects in the Solar System Using Spacewatch". The Astronomical Journal. 133 (4): 1247–1270. Bibcode:2007AJ....133.1247L. doi:10.1086/511155. S2CID 29114253.
  11. ^ Cowing, Keith. "17th moon of Jupiter discovered". Spaceref. Archived from the original on 18 October 2019. Retrieved 3 November 2021.
  12. ^ "5145 Pholus (1992 AD)". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  13. ^ "9965 GNU". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  14. ^ "SDSS/SMASS asteroid taxonomy".
  15. ^ "9885 Linux". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  16. ^ "9882 Stallman". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  17. ^ "9793 Torvalds". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  18. ^ "20000 Varuna". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  19. ^ "coms06".
  20. ^ "1998 KY26". JPL Small-Body Database Browser. Jet Propulsion Laboratory.
  21. ^ "65803 Didymos". 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.
  29. ^ "Spacewatch Recovery of Long-Lost Asteroid (719) Albert". spacewatch. The University of Arizona. Retrieved 3 November 2021.