900-999
- 900: Moriyama (Moriyama, Shiga, Japan)
- 901: Tajimi
- 902: Ootake
- 903: Fukuchiyama and Kannabe (Fukuchiyama and Kannabe Observatory, Japan)
- 904: Go-Chome and Kobe-Suma
- 905: Nachi-Katsuura Observatory
- 906: Cobram
- 907: Melbourne
- 908: Toyama
- 909: Snohomish Hilltop Observatory
- 910: Caussols-ODAS
- 911: Collins Observatory, Corning Community College, Corning, New York, USA
- 912: Carbuncle Hill Observatory, Greene
- 913: Observatorio Kappa Crucis, Montevideo
- 914: Underwood Observatory, Hubbardston
- 915: River Oaks Observatory, New Braunfels, Texas, USA
- 916: Oakley Observatory, Terre Haute, Indiana, USA
- 917: Pacific Lutheran University Keck Observatory
- 918: Badlands Observatory, Quinn, Sorth Dakota, USA
- 919: Desert Beaver Observatory, Arizona, USA
- 920: RIT Observatory, Rochester, New York, USA (Rochester Institute of Technology)
- 921: SW Institute for Space Research, Cloudcroft, Arizona, USA
- 922: Timberland Observatory, Decatur
- 923: The Bradstreet Observatory, St. Davids, Pennsylvania, USA
- 924: Observatoire du Cégep de Trois-Rivières
- 925: Palominas Observatory
- 926: Tenagra II Observatory, Arizona, USA
- 927: Madison-YRS
- 928: Moonedge Observatory, Northport
- 929: Port Allen
- 930: Tahiti
- 931: Punaauia, French Polynesia
- 932: John J. McCarthy Obs., New Milford
- 933: Rockland Observatory, Sierra Vista
- 934: Poway Valley
- 935: Wyrick Observatory, Haymarket
- 936: Ibis Observatory, Manhaatan
- 937: Bradbury Observatory, Stockton-on-Tees
- 938: Linhaceira
- 939: Observatorio Rodeno
- 940: Waterlooville
- 941: Observatorio Pla D'Arguines
- 942: Grantham
- 943: Peverell
- 944: Observatorio Geminis, Dos Hermanas
- 945: Observatorio Monte Deva
- 946: Ametlla de Mar Observatory
- 947: Saint-Sulpice
- 948: Pymoor
- 949: Durtal
- 950: La Palma, Spain (Roque de los Muchachos Observatory)
- 951: Highworth
- 952: Marxuquera
- 953: Montjoia
- 954: Teide Observatory, Tenerife, Canary Islands, Spain
- 955: Sassoeiros
- 956: Observatorio Pozuelo
- 957: Merignac
- 958: Observatoire de Dax
- 959: Ramonville Saint Agne
- 960: Rolvenden
- 961: City Observatory, Edinburgh
- 962: Gandia
- 963: Werrington
- 964: Southend Bradfield
- 965: Observação Astronómica no Algarve, Portimão, Portugal (COAA: Centro de Observação Astronómica no Algarve)
- 966: Church Stretton
- 967: Greens Norton
- 968: Haverhill
- 969: London-Regents Park, London, United Kingdom (George Bishop's Observatory, Regent's Park, 1836-1861)
- 970: Chelmsford
- 971: Lisbon
- 972: Dun Echt
- 973: Harrow
- 974: Genoa
- 975: Valencia
- 976: Leamington Spa
- 977: Markree (Markree Observatory, County Sligo, Ireland)
- 978: Conder Brow
- 979: South Wonston
- 980: Lancaster
- 981: Armagh
- 982: Dunsink Observatory, Dublin, Ireland
- 983: San Fernando
- 984: Eastfield
- 985: Telford
- 986: Ascot
- 987: The Isle of Man Observatory
- 988: Glasgow
- 989: Wilfred Hall Observatory, Preston
- 990: Madrid, Spain (Observatorio Astronómico de Madrid)
- 991: Liverpool (since 1867)
- 992: Liverpool (before 1867)
- 993: Woolston Observatory
- 994: Godalming
- 995: Durham (Durham University Observatory)
- 996: Oxford (Radcliffe Observatory)
- 997: Hartwell
- 998: London-Mill Hill (University of London Observatory)
- 999: Bordeaux-Floirac (Observatoire de Bordeaux)
Read more about this topic: List Of Observatory Codes