The mountain is host to several ongoing observing projects using the onsite facilities. The observatory has two primary nighttime telescopes: the 60-inch telescope, built in 1908, is home to the HK Project; the 100-inch (Hooker) telescope, built in 1917, has a new instrument for Adaptive Optics.
Two solar observatories have been in operation since the early days of the Observatory. The 60-foot tower telescope, operated by USC, is part of a worldwide network monitoring helioseismology. The 150-foot tower telescope, operated by UCLA, investigates long-term changes of solar magnetic activity.
There are also three interferometers on site. The Infrared Spatial Interferometer (operated by U.C. Berkeley), and the Naval Research Laboratory's Optical Interferometer have been in operation for several years.
The third interferometer, the CHARA array (a Georgia State University project), is now under construction, and saw first light in 1999. Finally, the Telescopes in Education Project (TIE) operates a 24-inch telescope and the Snow Solar Telescope to bring research-quality astronomy into classrooms around the world.
![[Adaptive Optics]](Images/ao-off.gif)
![[Helioseismology]](Images/helio-off.gif)
![[Infrared Interferometry]](Images/isi-off.gif)
![[Optical Interferometry]](Images/nrl-off.gif)
![[Solar-Stellar Connection]](Images/hk-off.gif)
![[Telescopes in Education]](Images/tie-off.gif)
![[Science Menu]](Images/sm-on.gif)
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![[High Resolution Angular Astronomy]](Images/chara-off.gif)
![[Solar Magnetic Activity Cycles]](Images/ucla-off.gif)