500-599
- 500: Geocentric
- 501: Herstmonceux
- 502: Colchester
- 503: Cambridge
- 504: Le Creusot, France
- 505: Simon Stevin
- 506: Bendestorf
- 507: Nyenheim
- 508: Zeist
- 509: La Seyne sur Mer
- 510: Siegen
- 511: Observatoire de Haute-Provence, France
- 512: Leiden (before 1860)
- 513: Lyons
- 514: Mundenheim (1907-1913)
- 515: Volkssternwarte Dhaun, near Kirn
- 516: Hamburg (before 1909), German Empire
- 517: Geneva (from 1967), Switzerland
- 518: Marine Observatory, Hamburg
- 519: Meschede
- 520: Bonn
- 521: Bamberg
- 522: Observatory of Strasbourg (Observatoire de Strasbourg)
- 523: Frankfurt
- 524: Mannheim
- 525: Marburg, Germany
- 526: Kiel
- 527: Altona
- 528: Göttingen
- 529: Christiania
- 530: Lübeck
- 531: Collegio Romano, Rome, Italy (Osservatorio del Collegio Romano)
- 532: Munich, Germany (Universitäts-Sternwarte München, Bogenhausener Sternwarte; a.k.a. Königlichen Sternwarte zu Bogenhausen)
- 533: Padua
- 534: Leipzig (since 1861)
- 535: Palermo (Osservatorio Astronomico di Palermo "Giuseppe S. Vaiana", Sicily)
- 536: Berlin-Babelsberg (Berlin Observatory after 1913)
- 537: Urania Observatory, Berlin (Urania Sternwarte)
- 538: Pola, Croatia (Kaiserlichen und Koniglichen Kriegsmarine Pola Sternwarte; Austro-Hungarian Imperial Naval Observatory in Pola, now Pula, Croatia)
- 539: Kremsmünster
- 540: Linz (Davidschlag Observatory; Private Observatory Meyer/Obermair; Sternwarte Davidschlag, Austria)
- 541: Prague Observatory
- 542: Falkensee
- 543: Leipzig (before 1861), German Empire
- 544: Wilhelm Foerster Observatory, Berlin (Wilhelm-Foerster-Sternwarte)
- 545: Vienna Observatory (before 1879), Austria-Hungary
- 546: Oppolzer Observatory, Vienna
- 547: Breslau
- 548: Berlin (1835-1913) (Berliner Sternwarte, Berlin Observatory, before 1913)
- 549: Uppsala (Uppsala Astronomical Observatory (UAO); Astronomiska observatoriet i Uppsala)
- 550: Schwerin
- 551: Hurbanovo, formerly O'Gyalla
- 552: Osservatorio S. Vittore, Bologna, Italy (Osservatorio San Vittore)
- 553: Chorzów
- 554: Burgsolms Observatory, Wetzlar
- 555: Cracow-Fort Skała
- 556: Reintal, near Munich
- 557: Ondřejov Observatory (Observatoř Ondřejov, Czech Republic)
- 558: Warsaw
- 559: Serra La Nave
- 560: Madonna di Dossobuono (Osservatorio Madonna di Dossobuono, Italy)
- 561: Piszkéstető Stn. (Konkoly) (Piszkéstető Station, Konkoly Obszervatórium, Budapest)
- 562: Figl Observatory, Vienna
- 563: Seewalchen
- 564: Herrsching
- 565: Bassano Bresciano (Osservatorio Astronomico di Bassano Bresciano, Italy)
- 566: Haleakala-NEAT/GEODSS, Hawaii, USA
- 567: Chions, Italy (Osservatorio di Chions - Chaonis Observatory)
- 568: Mauna Kea Observatory, Hawaii, USA
- 569: Helsinki
- 570: Vilnius (since 1939)
- 571: Cavriana, Italy (Osservatorio "Giordano Bruno")
- 572: Cologne
- 573: Eldagsen
- 574: Gottolengo
- 575: La Chaux de Fonds
- 576: Burwash
- 577: Metzerlen Observatory
- 578: Linden Observatory
- 579: Novi Ligure
- 580: Graz
- 581: Sedgefield
- 582: Orwell Park
- 583: Odessa-Mayaki
- 584: Leningrad
- 585: Kiev comet station
- 586: Pic du Midi (Observatoire du Pic du Midi, France)
- 587: Sormano (Osservatorio Astronomico Sormano, Italy)
- 588: Eremo di Tizzano
- 589: Santa Lucia Stroncone", Italy (Osservatorio Astrometrico Santa Lucia Stroncone)
- 590: Metzerlen
- 591: Resse Observatory
- 592: Solingen, Germany
- 593: Monte Argentario
- 594: Monte Autore
- 595: Farra d'Isonzo (Osservatorio Astronomico di Farra d'Isonzo, Italy)
- 596: Colleverde di Guidonia (Osservatorio Colleverde di Guidonia, Italy)
- 597: Springe
- 598: Loiano (Osservatorio Astronomico di Loiano, Italy)
- 599: Campo Imperatore-CINEOS (Osservatorio di Campo Imperatore, Italy)
Read more about this topic: List Of Observatory Codes