The H.S. Mendenhall Observatory

Oklahoma State University's observatory is situated under dark skies southwest of Stillwater, Oklahoma. Designed for astronomical research and regular public viewings, it is home to the largest and most advanced telescope within 300 miles. Pictured at right are the site in 2006, dome, telescope, and Control Building (interior not yet complete). 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 illustration at bottom right (copyright by Toby Wilson) shows how the observatory will look when fully completed. The Control Building now occupies the three-o'clock position in the aerial view at top right. The circular fence encloses the dome and a central concrete pad for portable telescopes. 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 September 10, 2018


The Control Building will make the observatory an outstanding research facility, and a great place for sky viewings. Construction of the Control Building was divided into two phases. The finished Control Building will contain a restroom, kitchenette, telescope control room, and equipment storeroom, all heated and cooled. It is pictured at right in the bottom illustrations.


Thanks to generous private support, Phase One construction began in November 2016 and was completed in June 2017. This phase included the building's exterior "shell", interior walls, electric power and lighting, heating and air conditioning, and a sidewalk connecting to the central observing pad.


Phase Two construction began in June 2018, and should take about two months. Thus far completed are a screening fence for blocking wind and stray light, and the connection to a nearby water line. As the photos below show, the Control Building’s computer countertop, kitchenette (opposite the computer area) and restroom, and the dome’s air conditioner, are essentially finished. Just the septic system remains to be installed.



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.

Future development of the observatory will include modernization of the robotic telescope's complex control system. 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 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.