The H.S. Mendenhall Observatory

Aerial Photo of Mendenhall Observatory

Aerial Photo of 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 above and at right are the site, dome, control building, and 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 central concrete pad is for portable telescopes. There is ample space for outdoor star parties and future structures.


The observatory's smaller, first telescope was in the dome until its replacement by the 24-inch telescope. The 14-inch Telescope Gallery shows the telescope, the students who used it, and pictures and video of what they observed.


Observatory Construction and Fundraising News

Updated March 6, 2019


The control building is designed to make the observatory an outstanding research facility, and a great place for star parties. The control building contains a restroom, kitchenette, telescope control room, and equipment storeroom, all heated and cooled.


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


Continued private support allowed construction to resume in June 2018.  Work was completed by the end of the year: The interior was finished out, the semicircular screening fence for blocking wind and stray light was added, connection was made to a nearby water line, and the septic system was installed. The building awaits water heater certification, and inspection by the fire marshall.


The finished observatory 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.


Funding is now being sought for upgrading 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 and TV

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 also appears in the five-part series titled "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.


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.