800-899
- 800: Harvard Observatory, Arequipa, Peru (Boyden Station)
- 801: Oak Ridge Observatory, Massachusetts, USA
- 802: Harvard Observatory, Cambridge, Massachusetts, USA (Harvard College Observatory)
- 803: Taunton, Massachusetts, USA
- 804: Santiago-San Bernardo
- 805: Santiago-Cerro El Roble, Santiago, Chile (Cerro El Roble Observatory)
- 806: Santiago-Cerro Calán, Santiago, Chile (National Astronomical Observatory (Chile)
- 807: Cerro Tololo Observatory, La Serena, Coquimbo, Chile (Cerro Tololo Inter-American Observatory)
- 808: El Leoncito, San Juan, Argentina (became the Dr. Carlos U. Cesco Observatory (Estación de Altura Carlos Ulrico Cesco) in 1990; seems to be the same as the Observatorio Félix Aguilar, San Juan National University)
- 809: European Southern Observatory, La Silla, Coquimbo, Chile (La Silla Observatory)
- 810: Wallace Observatory, Westford, Massachusetts, USA (George R. Wallace Jr. Astrophysical Observatory (WAO))
- 811: Maria Mitchell Observatory, Nantucket, Massachusetts, USA
- 812: Viña del Mar
- 813: Santiago-Quinta Normal (1862-1920), Santiago, Chile (National Astronomical Observatory (Chile)
- 814: North Scituate
- 815: Santiago-Santa Lucia (1849-1861), Santiago, Chile (National Astronomical Observatory (Chile)
- 816: Rand Observatory
- 817: Sudbury, Massachusetts, USA
- 818: Gémeaux Observatory, Laval, Québec, Canada (Observatoire Gémeaux)
- 819: Val-des-Bois, Québec, Canada
- 820: Tarija
- 821: Córdoba-Bosque Alegre, Córdoba, Argentina (Estación Astrofísica de Bosque Alegre, Observatorio Astronómico de Córdoba)
- 822: Córdoba, Argentina (Observatorio Astronómico de Córdoba)
- 823: Fitchburg
- 824: Lake Clear
- 825: Granville
- 826: Plessissville, Québec, Canada
- 827: Saint-Félicien, Québec, Canada
- 828: Assonet
- 829: Complejo Astronómico El Leoncito, San Juan Province, Argentina (CASLEO)
- 830: Hudson
- 831: Rosemary Hill Observatory, University of Florida, Florida, USA
- 832: Etters
- 833: Obs. Astronomico de Mercedes, Buenos Aires
- 834: Buenos Aires-AAAA, Argentina
- 835: Drum Hill Station, Chelmsford
- 836: Furnace Brook Observatory, Cranston
- 837: Jupiter
- 838: Dayton
- 839: La Plata (La Plata Astronomical Observatory; Observatorio Astronómico de La Plata)
- 840: Flint, Michigan, USA
- 841: Martin Observatory, Blacksburg, Virginia, USA
- 842: Gettysburg College Observatory, Pennsylvania, USA
- 843: Emerald Lane Observatory, Decatur, Illinois, USA
- 844: Los Molinos
- 845: Clinton B. Ford Observatory, Ithaca, New York, USA
- 846: Principia Astronomical Observatory, Elsah, Illinois, USA
- 847: Lunar Cafe Observatory
- 848: Tenagra Observatory, Cottage Grove, Oregon, USA
- 849: Everstar Observatory, Olathe, Kansas, USA (EverStaR Observatory)
- 850: Cordell-Lorenz Observatory, Sewanee, Tennessee, USA
- 851: Burke-Gaffney Observatory, Halifax
- 852: River Moss Observatory, St. Peters
- 853: Biosphere 2 Observatory
- 854: Sabino Canyon Observatory, Tucson, Arizona, USA
- 855: Wayside Observatory, Minnetonka, Minnesota, USA
- 856: Riverside
- 857: Iowa Robotic Observatory, Sonoita, Arizona, USA
- 858: Tebbutt Observatory, Edgewood
- 859: Wykrota Observatory-CEAMIG, Minas Gerais, Brazil (Observatório Wykrota - CEAMIG (Centro de Estudos Astronômicos de Minas Gerais))
- 860: Valinhos
- 861: Barão Geraldo
- 862: Saku
- 863: Furukawa
- 864: Kumamoto (KCAO (Kumamoto Civil Astronomical Observatory), Kumamoto, Kumamoto, Japan)
- 865: Emmy Observatory, New Paltz
- 866: U.S. Naval Academy, Michelson
- 867: Saji Observatory
- 868: Hidaka Observatory
- 869: Tosa
- 870: Campiñas (Observatório de Campinas, a.k.a. Observatório Municipal de Campinas "Jean Nicolini")
- 871: Akou
- 872: Tokushima
- 873: Kurashiki Observatory
- 874: Itajuba
- 875: Yorii
- 876: Honjo
- 877: Okutama
- 878: Kagiya
- 879: Tōkai (Tōkai, Aichi, Japan)
- 880: Rio de Janeiro
- 881: Toyota
- 882: JCPM Oi Station
- 883: Shizuoka (Shizuoka, Shizuoka, Japan)
- 884: Kawane
- 885: JCPM Yakiimo Station
- 886: Mishima (Mishima, Shizuoka, a.k.a. Susono, Shizuoka, Japan)
- 887: Ojima (Ojima, Gunma, Japan)
- 888: Gekko Observatory
- 889: Karasuyama (Karasuyama, Tochigi, Japan)
- 890: JCPM Tone Station
- 891: JCPM Kimachi Station
- 892: YGCO Hoshikawa and Nagano Stations
- 893: Sendai Municipal Observatory (Sendai Astronomical Observatory)
- 894: Kiyosato
- 895: Hatamae
- 896: Yatsugatake South Base Observatory (near 386 Yatsugatake-Kobuchizawa)
- 897: YGCO Chiyoda Station (YGCO: Yamaneko Group of Comet Observers)
- 898: Fujieda (Fujieda, Shizuoka, Japan)
- 899: Toma
Read more about this topic: List Of Observatory Codes