The H.S. Mendenhall Observatory

Oklahoma State University's observatory is situated under dark skies southwest of Stillwater, Oklahoma. It is home to the largest and most advanced telescope in Oklahoma and also within 300 miles. Pictured at right are the dome, the control building (now being built), and the telescope. Visit the 24-inch Telescope Gallery to view the first images made with it.


The observatory's layout is derived from a conceptual design by Stanly E Black, AIA, Architect, Boston, Massachusetts. The circular fence encloses the dome and a central concrete pad for portable telescopes. The control building is going up at the three-o'clock position in the aerial view. There is ample space for outdoor stargazing and additional structures. Visit the Construction Photo Archive to see the dome being built.


The observatory's smaller, first telescope was in service until May 2006. Visit the 14-inch Telescope Gallery to view images and videos showing the first telescope, the students who used it, and the objects they observed.



Control Building Construction and Fundraising News

Updated March 2017


The completed Control Building will contain a restroom, kitchenette, telescope control room, and equipment storeroom, all heated and cooled.

Generous private support enabled phase 1 construction of the Control Building to begin in November 2016. It is pictured at right in the bottom illustration (copyright by Toby Wilson). This phase includes the building's exterior "shell", interior walls, electric power and lighting, heating and air conditioning, and a sidewalk connecting to the central observing pad.

Fundraising continues for phase 2 construction, which includes connection to the water supply, restroom and kitchenette plumbing, and the septic system.

The completed Control Building will make the observatory an outstanding research facility for students and faculty, and a great place for sky viewings by astronomy classes and the public.

The Control Building will enable OSU to introduce an astronomy minor, unique in Oklahoma, that incorporates modern observatory experience. OSU students who minor in astronomy and major in physics or related fields will be ready for exciting, well-paying employment after graduation in industry, science, and defense.

Help OSU complete the observatory! Naming opportunities are available. For more information, please download the illustrated, four-page description of the Control Building project in PDF format.

Please note that the National Science Foundation, National Aeronautics and Space Administration, US Air Force and other federal entities do not fund the construction of buildings — only equipment purchases and research operations.

If you would like to contribute, please click here to make an instant donation to OSU Foundation account 22-40400, or contact Dr. Peter Shull and the OSU Foundation.



The Observatory on YouTube, TV and Radio

Click here to see the observatory on YouTube. This 6-minute video includes action shots of the telescope and dome, and interviews featuring OSU's president and two undergraduates.


The observatory is also in the five-part series entitled "Wonders of the Solar System" produced by the British Broadcasting Corporation (BBC). The observatory appears 34 minutes into the second episode, "Order out of Chaos". The series premiered in 2010 in the UK and the USA, and is commercially available on DVD. To see pictures related to the BBC's visit to Stillwater in 2009, click here.


On March 2, 2010, the Oklahoma Center for the Advancement of Science and Technology (OCAST) recorded a one-hour interview about the observatory with its director that was broadcast the following weekend across Oklahoma by ten radio stations. Click here to download an MP3 file of the broadcast. The actual interview starts 15 minutes into the program.



Stillwater Clear Sky Chart

Use the Stillwater Clear Sky Chart below to view a map of expected weather conditions for the Mendenhall Observatory. First click on the chart below. In the window that then opens, clicking one of the little squares in the top row will display a map of predicted cloud cover for the corresponding date and local time.


The Stillwater Clear Dark Sky Calendar



Dr. H.S. Mendenhall

Dr. H.S. MendenhallThe observatory is named for Harrison Shepler Mendenhall, Oklahoma State University's first astronomer.


Dr. Mendenhall earned his Ph.D. in astrophysics at the University of California at Berkeley, and served on OSU's faculty as a professor of mathematics and astronomy from 1937 until his retirement in 1968. During World War II, he taught navigation to countless air cadets as a lieutenant and captain in the U.S. Army Air Corps. Dr. Mendenhall died on March 20, 2000, at the age of 97.


Dr. Mendenhall's Personal TelescopeThis photograph shows Dr. Mendenhall's personal telescope, a 4-inch refractor built in the early 1890's, set up on the central observing pad.