The major instrument on Mt. Hopkins is the MMT Observatory's 6.5-m-diameter optical telescope (operated jointly by SAO with the University of Arizona). Others include a 10-m gamma-ray airshower Cerenkov telescope as well as the Peters Automated Infrared Imaging Telescope (PAIRITEL), a 1.3-m infrared telescope (formerly the northern 2MASS telescope, now operated by SAO); a 1.2-m imaging optical/infrared telescope; and the 1.5-m Tillinghast spectroscopic telescope. FLWO is also home to HAT, the Hungarian Automated Telescope.

The Las Campanas Observatory on Cerro Las Campanas in Chile, operates twin 6.5-m optical telescopes for a consortium of institutions, which includes Harvard University, the Carnegie Observatories, MIT, the University of Michigan, and the University of Arizona. Separated by 60 m, the twin telescopes afford fine "natural seeing," from an elevation of 2400 m (8000 feet) in the Chilean Andes and unparalleled access to the Southern Hemisphere skies for astronomers.

The MMT Observatory, a 6.5-meter-diameter optical telescope, is located on the summit of Mt. Hopkins at the Fred Lawrence Whipple Observatory, 30 miles south of Tucson, Arizona. The telescope (operated jointly by SAO and the University of Arizona) includes a suite of advanced wide-field imagers and spectrographs developed and deployed for the MMT by SAO scientists. This innovative facility was recently converted to a single mirror.

The South Pole Telescope (SPT), a 10-meter-diameter telescope located at the National Science Foundation's South Pole research station, achieved first light in February 2007. Designed to conduct large-area millimeter- and submillimeter-wave surveys of faint, low-contrast emission, this telescope is a collaboration among the University of Chicago, University of California (Berkeley), Case Western Reserve University, University of Illinois, and SAO. It is funded by the National Science Foundation Office of Polar Programs, private foundation grants, and the Kavli Institute for Cosmological Physics.

The Submillimeter Array is an 8-element interferometer operating in the wavelength range of 0.3 to 2 millimeters, located atop Mauna Kea in Hawaii. It is a collaboration between SAO and the Institute of Astronomy and Astrophysics of the Academia Sinica of Taiwan.

For over three decades the CfA 1.2 meter telescope and its twin instrument in Chile have been mainly dedicated to obtaining what is by far the most extensive, uniform, and widely-used survey of dense, star-forming molecular clouds in our Galaxy. A total of 24 PhD dissertations have so far been written based on observations or instrumental work with these telescopes, and many more undergraduate students have participated in the observations either in course laboratories or as observing assistants.

VERITAS consists of an array of four 12-m optical reflectors for gamma-ray astronomy. The design, based on an existing 10-m gamma-ray telescope at Whipple Observatory, consists of an array of imaging telescopes deployed such that they permit the maximum versatility and give the highest sensitivity in the 50 GeV-50 TeV band. Funded by NSF, DOE, and SAO, it is operated by SAO for a collaboration of colleges and universities worldwide.