| P.M.P.H.R. Deep Sky Observatory | Italia | Atina | — |
| P2 Observatory | Estados Unidos | Mayhill | — |
| Pachmarhi Telescope Array | India | — | — |
| Pacific Lutheran University Keck Observatory | Estados Unidos | Parkland | — |
| Pacific Northwest Regional Observatory | Estados Unidos | — | — |
| Pacific Sky Observatory observatory | Estados Unidos | Saipan Municipality | — |
 Palanga Observatory | Lituania | Palanga | — |
| Palazzo Bindi Sergardi observatory | Italia | Siena | — |
| Palestrina observatory | Italia | Palestrina | — |
| Palisades-Dows Observatory | Estados Unidos | Iowa | — |
| Pallerols observatory | España | Pallerols | — |
| Palmer Divide Observatory | Estados Unidos | Colorado Springs | — |
| Palmerston North observatory | Nueva Zelanda | Palmerston | — |
| Palo Alto observatory | Estados Unidos | Palo Alto | — |
| Palomar Mountain-DSS | Estados Unidos | Palomar Mountain | — |
| Palominas Observatory | Estados Unidos | Sierra Vista Southeast | — |
| Pamatai Magnetic Observatory | Francia | Polinesia Francesa | — |
| Pampilhosa da Serra Observatory | Portugal | — | — |
 Pan-STARRS | Estados Unidos | Maui County | — |
| Panagjurishte Magnetic Observatory | Bulgaria | Pazardzhik | 556 m |
| Panameno observatory | Chile | San Pedro de Atacama | — |
 Pandora | Estados Unidos | — | — |
| Panker observatory | Alemania | Panker | — |
 Panská Ves observatory | República Checa | Dubá | — |
| Panzano Observatory | Italia | Castelfranco Emilia | — |
| PAO observatory | Italia | Prato | — |
| Para Todos Remote Observatory | España | — | — |
| Paratunka Magnetic Observatory | Rusia | — | — |
 Parc Astronòmic Montsec | España | Ager | — |
 Pardubice observatory | República Checa | Pardubice | 230 m |
| Parma observatory | Italia | Parma | — |
| Partizanske observatory | Eslovaquia | Trenčín | — |
| PASTIS Observatory | Francia | Banon | — |
 Paul Robinson Observatory | Estados Unidos | Municipio de Lebanon | — |
 Paul Wild Observatory | Australia | New South Wales | — |
| Paus observatory | España | Sabadell | — |
 Peach Mountain Observatory | Estados Unidos | Míchigan | — |
| Pear Tree observatory | Estados Unidos | Valparaiso | — |
| Penn Heights Observatory | Reino Unido | Rickmansworth | — |
| Penrith Observatory | Australia | New South Wales | 60 m |
| Penteli Magnetic Observatory | Grecia | Dionisos Municipality | — |
 Penteli Observatory | Grecia | municipio de Penteli | — |
| Penwortham observatory | Australia | Penwortham | — |
| Penzing Astrometric observatory | Austria | Viena | — |
| Perak Observatory | Malasia | Manjung | — |
| Perkins Observatory | Estados Unidos | Delaware | — |
| Perpignan observatory | Francia | Perpiñán | — |
 Perrott's Folly | Reino Unido | Birmingham | — |
 Perth Observatory | Australia | City of Kalamunda | 428 m |
| Peschiera del Garda observatory | Italia | Peschiera del Garda | — |
| PESCOPE observatory | Sudáfrica | Puerto Elizabeth | — |
 Peterberg Observatory | Alemania | Nohfelden | 576 m |
| Petit Jean Mountain observatory | Estados Unidos | Petit Jean Mountain | — |
| Petit Sant Feliu observatory | España | San Feliú de Llobregat | — |
| Peverell observatory | Reino Unido | City of Plymouth | — |
| PGC observatory | España | Fregenal de la Sierra | — |
 Philippine Institute of Volcanology and Seismology | Filipinas | — | — |
| Phillips Academy Observatory | Estados Unidos | Andover | — |
| Phoebe Waterman Haas Public Observatory | Estados Unidos | Washington D. C. | — |
| Phuthuy Magnetic Observatory | Vietnam | — | — |
| Physikalisch-Meteorologisches Observatorium Davos / World Radiation Center | Suiza | Davos | — |
| Piazzano Observatory | Italia | Empoli | — |
 Pic du Midi Observatory | Francia | Bagnères-de-Bigorre | 2.877 m |
| Picard observatory | Austria | — | — |
 Pico dos Dias Observatory | Brasil | Brasópolis | 1.864 m |
| Piconcillo observatory | España | Piconcillo | — |
| Picoto Observatory | Portugal | Freguesia de Carreira | — |
| Piera Observatory | España | Piera | — |
 Pierre Kauffman Radio Observatory | Brasil | São Paulo | 819 m |
| Pieta observatory | Malta | Pietà | — |
| Pieterse Planetarium | — | — | — |
| Pilar Magnetic Observatory | Argentina | — | — |
| Pin Oak Observatory | Estados Unidos | Fort Madison | — |
 Pine Mountain Observatory | Estados Unidos | Oregón | — |
| Pineapple Observatory | Estados Unidos | Frederick | — |
| Pinsoro Observatory | España | Pinsoro | — |
| Pinto Valley observatory | Estados Unidos | San Bernardino County | — |
 Piombino Observatory | Italia | Piombino | 55 m |
| Plana Geodetic Observatory | Bulgaria | Plana | 1.300 m |
 Planck | — | — | — |
| Planetario de Serón-Almería | España | Serón | — |
| Planetarium de Vaulx-en-Velin Observatory | Francia | Vaulx-en-Velin | — |
 Planetarium Halle-Kanena | Alemania | Halle | — |
 Planetarium Negara | Malasia | Kuala Lumpur | — |
 Planetarium České Budějovice | República Checa | České Budějovice 7 | — |
 Planetary astronomical observatory of Anzi | Italia | Anzi | — |
 Planetology and Astrophysics Institute of Grenoble | Francia | Grenoble | — |
 Planetron | Países Bajos | Westerveld | — |
| Platanus Observatory | Polonia | Lusówko | — |
| Plateau Observatory | — | Región del Tratado Antártico | — |
 PLATO | — | — | — |
| Platteville Atmospheric Observatory | Estados Unidos | Colorado | — |
| Pleasant Groves Observatory | Estados Unidos | Pleasant Groves | — |
| Pleasanton observatory | Estados Unidos | Pleasanton | — |
| Pleiade Observatory | Italia | Pescantina | 90 m |
| Pleiades observatory | Canadá | Mandeville | — |
| Plessisville observatory | Canadá | Plessisville | — |
| Plomer observatory | Argentina | Buenos Aires | — |
| Plonsk observatory | Polonia | Płońsk | — |
| Plzeň observatory and planetarium | República Checa | Pilsen | 325 m |
| Po Leung Kuk observatory | República Popular China | Tuen Mun | — |
 Polaris Csillagvizsgáló | Hungría | Óbuda-Békásmegyer | — |
| Polaris observatory | Hungría | Budapest | — |
| Polino astronomical observatory | Italia | Polino | — |
| Polonia Observatory | Chile | San Pedro de Atacama | — |
| Polop observatory | España | Polop | — |
| Pommier observatory | Francia | Chapdes-Beaufort | — |
| Ponferrada observatory | España | Camponaraya | — |
| Pont-à-Mousson Observatory | Francia | Pont-à-Mousson | — |
| Ponte Uso observatory | Italia | cementerio de Sogliano al Rubicone | — |
| Popocatépetl Volcano Observatory | México | — | — |
| Popovich Observatory | Ucrania | Ivanivka | — |
| Popular Observatory in Belgrade | Serbia | Belgrado | — |
| Port Alfred Magnetic Observatory | French Southern and Antarctic Lands | — | — |
| Port Stanley Magnetic Observatory | Islas Malvinas | — | 130 m |
| Port-aux-Francais Magnetic Observatory | French Southern and Antarctic Lands | — | — |
| Portage Lake Observatory | Estados Unidos | Míchigan | — |
| Portland Bird Observatory | Reino Unido | — | — |
| Posadas Observatory | España | Posadas | — |
| Possum Observatory | Nueva Zelanda | Gisborne | — |
| Poste-de-la-Baleine Magnetic Observatory | Canadá | — | — |
| Pousada dos Anoes Observatory | Brasil | São João d'Aliança | — |
| Povegliano Veronese observatory | Italia | Povegliano Veronese | — |
| Poway Valley observatory | Estados Unidos | Poway | — |
| Powell Observatory | Estados Unidos | Kansas | — |
 Poznań Observatory | Polonia | Poznań | — |
| Prairie Grass Observatory | Estados Unidos | Mulberry | — |
| Prairie Observatory | Estados Unidos | — | — |
 Prenzlau observatory | Alemania | Prenzlau | — |
| Preston Hills observatory | Estados Unidos | Celina | — |
 PRIMA | — | — | — |
 Prince Edward Point National Wildlife Area | Canadá | Condado de Prince Edward | — |
 Principia Astronomical Observatory | Estados Unidos | Misuri | — |
| Principia observatory | España | Málaga | — |
 Prishtina Observatory | Kosovo | Pristina | — |
| Promiod observatory | Italia | Châtillon | — |
| PROMPT observatory | Australia | Coonabarabran | — |
 Provencal Baronnies Observatory | Francia | Moydans | — |
| Proyecto HATNet | — | — | — |
| Prude Ranch observatory | Estados Unidos | Texas | — |
| PSU Greenbush Observatory | Estados Unidos | Greenbush | — |
 Public Observatory Mainz | Alemania | Distrito Centro | 94 m |
 Public Observatory Mercury | Países Bajos | Dordrecht | — |
| Public Observatory Philippus Lansbergen Foundation | Países Bajos | Middelburg | — |
 Public Observatory Regensburg | Alemania | Ratisbona | — |
| Puchenstuben observatory | Austria | Puchenstuben | — |
 Puckett Observatory | Estados Unidos | Georgia | — |
| Pueyrredon observatory | Argentina | La Lonja | — |
 Pujalt Observatory | Francia | Pujalt | 750 m |
| Pulkovo Station observatory | Italia | L'Aquila | — |
| Puna'auia observatory | Francia | Punaauia | — |
 PUNCH-NFI | Estados Unidos | — | — |
 PUNCH-WFI 1 | Estados Unidos | — | — |
| PUNCH-WFI 2 | Estados Unidos | — | — |
| PUNCH-WFI 3 | Estados Unidos | — | — |
 Purgathofer-Sternwarte | Austria | Klosterneuburg | — |
| Purple Mountain Observatory, Xuyi Station | República Popular China | Xuyi | — |
| Purple Mountain Observatory, Yao'an Station | República Popular China | Yao'an | — |
| Pushchino Radio Astronomy Observatory | Rusia | — | — |
| Putman Mountain Observatory | Estados Unidos | Loyal Valley | — |
 Putrajaya International Convention Centre | Malasia | Putrajaya | — |
| Puzol Observatory | España | Puzol | — |
| Pymoor observatory | Reino Unido | Downham | — |
| Pyongyang Astronomical Observatory | Corea del Norte | — | — |
 Pyramid International Laboratory-Observatory | Nepal | Khumbu Pasanglhamu | 5.050 m |