Cerro Tololo Inter-American Observatory LogoCerro Tololo Inter-American Observatory

Photograph of Cerro Tololo Inter-American Observatory 

Cerro Tololo Inter-American Observatory (CTIO), a Program of NOIRLab, is a complex of astronomical telescopes and instruments located approximately 500 km (310 miles) north of Santiago, and 80 km (50 miles) to the east of La Serena, Chile, at an altitude of 2200 meters (7200 feet). 

CTIO operates the Víctor M. Blanco 4-meter Telescope on Cerro Tololo, which features the Dark Energy Camera (DECam), a high-performance, wide-field CCD imager built to carry out the Dark Energy Survey (DES) (a US Department of Energy Office of Science-led project). It also operates the 4.1-meter Southern Astrophysical Research (SOAR) Telescope on the adjacent Cerro Pachón (a partnership between Ministério da Ciência, Tecnologia, Inovações e Comunicações Brazil, NOIRLab, the University of North Carolina at Chapel Hill, and Michigan State University). The Cerro Tololo 1.5-meter and 0.9-meter telescopes are being operated by the SMARTS Consortium with support from CTIO. Cerro Tololo also hosts 11 tenant observatories and research projects — in total around 40  telescopes, providing a platform for access to the southern hemisphere for US and worldwide scientific research.

Daytime guided tours of the facilities on Cerro Tololo are available on Saturdays all year round.

The astronomical community is honored to have the opportunity to conduct astronomical research on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the local communities in Chile.

CTIO is operated by NSF’s NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA).

Travel information for CTIO is available here.

Visit the CTIO Science site