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.

[1] Much of the information captured at TMO is now available through the Planetary Data System's Atmospheres Node, which is managed by NMSU.

[2] A second building, with a larger single dome, was completed at the opposite end of the ridgeline of Tortugas Mountain in 1967.

[6] In 2010, efforts to revive the observatory for use by the American Association of Variable Star Observers began.