Tortugas Mountain Observatory (TMO) is an astronomical observatory owned and operated by New Mexico State University (NMSU). It is located on Tortugas Mountain, also known locally as 'A' Mountain, in southern New Mexico (USA), approximately 8 kilometers (5.0 mi) southeast of Las Cruces and 4 kilometers (2.5 mi) east of the NMSU campus. Founded in 1963 under the supervision of Clyde Tombaugh, the observatory focused on observing the planets. Much of the information captured at TMO is now available through the Planetary Data System's Atmospheres Node, which is managed by NMSU. The two-dome observatory building was completed in 1964, though observing began with one of the telescopes in 1963. A second building, with a larger single dome, was completed at the opposite end of the ridgeline of To