K
| Name | Established | Location |
| Khajeh Nasiredin Observatory | ~1980 | Tabriz University, Tabriz, Iran |
| Kamioka Observatory | 1983 | Hida, Gifu, Japan |
| Kanzelhoehe Solar Observatory | 1943 | Villach, Austria |
| Karl Schwarzschild Observatory | 1960 | Jena, Germany |
| Keck Observatory | 1993 | Mauna Kea, Hawaii, USA |
| Keeble Observatory | 1963 | Ashland, Virginia, USA |
| Kennon Observatory | 1939 | Oxford, Mississippi, USA |
| Kepler Space Observatory | 2009 | Earth-trailing heliocentric orbit |
| Kevola Observatory | 1963 | Kevola, Finland |
| Kielder Observatory | 2008 | Kielder Forest, Northumberland, England, United Kingdom |
| Kirkwood Observatory | 1901 | Bloomington, Indiana, USA |
| Kitami Observatory | Hokkaidō, Japan | |
| Kitt Peak National Observatory | 1958 | Tucson, Arizona, USA |
| Kleť Observatory | 1957 | České Budějovice, Czech Republic |
| Kodaikanal Solar Observatory | 1899 | Palani, Tamil Nadu, India |
| Konkoly Observatory | 1871 | Budapest, Hungary |
| KOSMA observatory | 1985–2010 | Gornergrat, Switzerland |
| Kuffner observatory | 1884 | Austria |
| Kuiper Airborne Observatory | 1974 | 14 km in the stratosphere |
| Kvistaberg Observatory | Sweden | |
| Kyung Hee Observatory | 1992 | Seoul, South Korea |
Read more about this topic: List Of Astronomical Observatories