Tonantzintla Observatory () is an astronomical observatory located in the municipality of San Andrés Cholula in the Mexican state of Puebla. It consists of two adjacent facilities: the National Astrophysical Observatory of Tonantzintla ( - OANTON), operated by the National Institute of Astrophysics, Optics and Electronics (INAOE), and the National Astronomical Observatory - Tonantzintla (—OAN - Tonantzintla), operated by the National Autonomous University of Mexico (UNAM). OANTON is located on the INAOE campus, which includes numerous other buildings. OAN - Tonantzintla is located immediately to the east on mostly unused property. The observatory is located west of Puebla and east of Popocatépetl, eruptions of which sometimes interfere with observing.