There are currently thirteen working telescopes near the summit of Mauna Kea. Nine of them are for optical and infrared astronomy, three of them are for submillimeter wavelength astronomy and one is for radio astronomy. They include the largest optical/infrared  telescopes in the world (the Keck telescopes), the largest dedicated infrared telescope (UKIRT) and the largest submillimeter telescope in the world (the JCMT). The westernmost antenna of the Very Long Baseline Array (VLBA) is situated at a lower altitude two miles from the summit. 

Resources:

• Mauna Kea Observatories, Institute for Astronomy - University of Hawaii:

http://www.ifa.hawaii.edu/mko/

• Mauna Kea Observatories, Telescope link-list:

Optical/Infrared:

• UH 0.6-m educational telescope (University of Hawaii at Hilo)

http://www.astro.uhh.hawaii.edu/NewEducationalTelescope.php

• UH 2.2-m telescope (UH Institute for Astronomy)

http://www.ifa.hawaii.edu/88inch/

• IRTF - NASA Infrared Telescope Facility (NASA)
  

http://irtfweb.ifa.hawaii.edu/

• CFHT - Canada-France-Hawaii Telescope (Canada/France/UH)

http://www.cfht.hawaii.edu/

• UKIRT - United Kingdom Infrared Telescope (United Kingdom)

http://www.jach.hawaii.edu/UKIRT/

• Keck I/II - W. M. Keck Observatory (Caltech/University of California)

http://www.keckobservatory.org/

• Subaru Telescope (Japan)

http://www.naoj.org/

• Gemini Northern Telescope (USA/UK/Canada/Argentina/Australia/Brazil/Chile)

http://www.gemini.edu/

 

Submillimeter:

• CSO - Caltech Submillimeter Observatory (Caltech/NSF)

http://www.submm.caltech.edu/cso/

• JCMT - James Clerk Maxwell Telescope (UK/Canada/Netherlands)

http://www.jach.hawaii.edu/JCMT/

• SMA - Submillimeter Array (Smithsonian Astrophysical Observatory/Taiwan)

http://sma-www.harvard.edu/

 

Radio:

• VLBA - Very Long Baseline Array (NRAO/AUI/NSF)

http://www.nrao.edu/vlba/html/VLBA.html