Tenagra Observatory and Tenagra Observatory II are astronomical observatories in Cottage Grove, Oregon and Arizona. The observatories house heavily automated robotic telescopes.

Circa 2016, the observatory was utilized with the Katzman Automatic Imaging Telescope a member of the Lick Observatory and Tenagra Observatory Supernova Searches (LOTOSS).

Beginning in 2018, after a NASA grant to owner Michael Schwartz expired, control of the Arizona observatory was turned over to Gianluca Masi's Virtual Telescope project.

The observatory near Cottage Grove, Oregon was constructed c. 1998, and had a 14-inch (360 mm) Celestron Schmidt-Cassegrain with a SBIG CCD imager, probably upgraded to Apogee Instruments later.

The Arizona observatory at Patagonia, 20 miles from Nogales, began operations in 2000. Tenagra II is a custom-made 32-inch (810 mm) Ritchey-Chretien telescope manufactured by SciTech Astronomical Research, in operation since 2001. "Pearl" is a 16-inch (410 mm) f/3.75 corrected Newtonian. There is also a 24-inch (610 mm) SciTech Ritchey-Chretien, and another 14-inch Celestron.

The Oregon site was in use as of 2004 as a backup site, during the Southwest monsoon season.

The robotic telescopes can image 1,000 galaxies in an evening for supernova discovery. Using the Oregon Tenagra I telescope, its maker became "the first amateur to achieve consistent supernova discoveries" by using a robotic telescope "to patrol hundreds of galaxies each night".

The Oregon observatory reported 77 Minor Planet Electronic Circulars between 1999 and 2002.

The Oregon observatory discovered supernova SN 1997cx [pl].

Paulo R. Holvorcem (Porto Seguro, Bahia, Brazil) and Michael Schwartz (Patagonia, Arizona) discovered comet C/2011 K1 (Schwartz-Holvorcem) [uk] in May 2011.

Comet 274P/Tombaugh-Tenagra [fr] is named for the observatory and Clyde Tombaugh. Tombaugh initially discovered it in January 1931, but was not recovered until 2012. It was provisionally named Comet P/2012 WX_32 (Tenagra) when recovered by Michael Schwartz and Paulo R. Holvorcem using Tenagra II.

The observatory's Tenagra IV instrument, along with Palomar Observatory's Samuel Oschin telescope, was the second to image dwarf planet Sedna, providing confirmation of its discovery and refining its orbital parameters.

In 2018, Pearl imaged the Tesla Roadster in space, when it had a magnitude of 15.5, comparable to Pluto's moon Charon.

In 2018, imagery from the Arizona observatory was livestreamed by Gianluca Masi during the 2018 DV₁ close approach to Earth as a Virtual Telescope project outreach event. Images of the Tiangong-1 space station in its decaying orbit were livestreamed in 2018, a few days before reentry.

2013 Edgar Wilson Award

• List of asteroid-discovering observatories#Tenagra II Observatory
• List of minor planet discoverers
• "Darmok"
• Winer Observatory

• "List Of Observatory Codes (formatted, with external links)". Minor Planet Center. Retrieved November 25, 2022.
• "848 Tenagra Observatory, Cottage Grove". MPEC Observatory Browser. Minor Planet Center. Retrieved November 25, 2022.
• "926 Tenagra II Observatory, Nogales". MPEC Observatory Browser. Minor Planet Center. Retrieved November 25, 2022.
• Polakis, Tom (May 2004), "Robotic Observing: If Robotic-Controlled Telescopes Are the Future of Astronomical Observing, Then Tenagra Observatories Are Leading This Technological Revolution", Astronomy, 32 (5)
• Schwartz, Michael (1996). "Tenagra Observatory". Small Astronomical Observatories. Practical Astronomy. Springer. pp. 187–197. doi:10.1007/978-1-4471-0999-0_21. ISBN 978-3-540-19913-7.
• "Tenagra Observatories - An IAWN observing station in Arizona". International Asteroid Warning Network. c. 2018. Archived from the original on 2018-06-19. Retrieved November 25, 2022.
• Elenin, Leonid (June 7, 2011). "PostDateIcon". spaceobs.org.
• Holvorcem, R; Schwartz, M.; Ryan, W. H.; Ryan, E. V.; Buzzi, L.; Holmes, R.; Vorobjov, T.; Foglia, S.; Williams, G. V. (31 May 2011). Green, D. W. E. (ed.). "Comet C/2011 K1 (Schwartz-Holvorcem)". IAU Circular. 9211: 1. Bibcode:2011IAUC.9211....1H.
• Schwartz, M.; Jha, S.; Garnavich, P.; Challis, P.; Kirshner, R.; Berlind, P.; Hergenrother, C. W. (1997), Green, D. W. E. (ed.), "Supernova 1997cx in NGC 3057", IAU Circ., 6700: 1, Bibcode:1997IAUC.6700....1S
• Zionts, Arielle (July 11, 2017). "Local astronomer sets lens on public outreach". Nogales International.
• Holvorcem, P. R.; Schwartz, M.; Juels, C. W.; Breganhola, M.; Camargo, J.; Teixeira, R. (2003). "Astrometry of Near-Earth Asteroids Using Remotely-Operated Robotic Telescopes". Astronomy in Latin America, Second Meeting on Astrometry in Latin America and Third Brazilian Meeting on Fundamental Astronomy, Held 2–5 September 2002. 1 (1). ADeLA Publications: 91–100. Bibcode:2003ala..conf...91H.
• Beatty, J. Kelly (May 15, 2014), "Amateur comet hunters get 2013 award", Sky & Telescope, Now in its 15th year, the Edgar Wilson Award recognizes comet discoveries made by amateur observers. The 2013 awards honor seven dedicated individuals who scan the skies.
• Levy, David (2003). David Levy's Guide to Observing and Discovering Comets. Cambridge University Press. ISBN 978-0521520515.
• Schwartz, M.; Holvorcem, P. R.; Williams, G. V.; Marsden, C. L.; Sato, H.; Kowalski, R. A. (December 2012), Green, D. W. E. (ed.), "Central Bureau Electronic Telegrams, No. 3329, #1 (2012)", Central Bureau Electronic Telegrams, 3329: 1, Bibcode:2012CBET.3329....1S
• Minor Planet Electronic Circular 2004-E45 : 2003 VB12, Minor Planet Center, March 15, 2004
• Weitering, Hanneke (March 28, 2018). "Telescope Spots Doomed Chinese Space Station (Photo)". Space.com.
• Mobberley, Martin (2004). The New Amateur Astronomer. Springer London. ISBN 1852336633. [S]upernova patroller Michael Schwartz, director of his private "Tenagra" Observatory in Oregon, showed the way by acquiring one of the first Paramount GT1100 [computer controlled telescope mounts] and coupling it to a Celestron 14 Optical Tube Assembly ... Michael was really the first amateur to achieve consistent supernova discoveries by using the Paramount to patrol hundreds of galaxies each night.
• Sky & Telescope magazine [@skyandtelescope] (February 8, 2018). "Spotted: One Tesla Roadster in space" (Tweet) – via Twitter.
• Masi, Gianluca (February 8, 2018). "Elon Musk's Tesla Roadster imaged and filmed!". virtualtelescope.eu. Archived from the original on February 9, 2018. Retrieved February 9, 2018.
• Mack, Eric (March 2, 2018). "See the bus-size asteroid caught buzzing past Earth". CNet.

• Mobberley, Martin P. (October 2004), "A trio of supernova hunters", Sky & Telescope, 108 (4): 111, Bibcode:2004S&T...108d.111M

• Tenagra Observatories homepage at the Wayback Machine (archived October 17, 2018)