Crow Observatory

The Crow Observatory is open to the Washington University community on clear evenings, Monday through Thursday, during the fall and spring semesters. When we are on standard time, the open hours are 7:00 - 10:00 pm. When we are on daylight saving time the hours are 8:00 - 10:00 pm. Visitors can check here or phone 314-935-6278 during viewing hours to see if the Observatory is open.

The location is atop Crow Hall near the northeast corner of the WU Danforth Campus. You can enter the building through the south door, then go up the stairs and follow the signs. Admission is free, and members of the campus and local community are welcome. Groups numbering seven or more, or anyone who has special requirements must make advance reservations by calling 314-935-6276 during the day.

The main telescope has an aperture of 6 inches. This telescope was acquired by Washington University in 1863; although small by present-day standards, is of excellent quality. The observatory was originally on 18th Street in St. Louis, before the University moved to the Danforth campus after the 1904 World's Fair. Until 1950, the observatory stood west of Crow Hall. It was then closed and a new dome was constructed in the present location in 1954.

The Crow observatory was featured on the KETC (local PBS station) program Living St. Louis.

Objects Visible at Various Times

The Moon presents mountain ranges, plains, and countless craters. Best viewing is near first quarter when there is deep shadowing; near full moon, little contrast exists to bring out fine details.

The planets Venus, Mars, Jupiter, and Saturn are clearly visible at various times of the year.

"Deep-Sky Objects" located far beyond our solar system : most of these objects need a clear dark night to be seen well. On such nights, the Pleiades, or Seven Sisters star cluster, the Orion nebula, a gaseous region of star formation, and other objects can be viewed, but the atmosphere over St. Louis, as with most major cities, is not clear enough for viewing of faint extended objects.

A Brief History

At the inaugural ceremonies of Washington University in 1857, William Greenleaf Eliot, the first chancellor, announced that the local philanthropist, James Yeatman, had donated $1,500 for the making of a superior telescope. The lenses for the 6-inch refractor, made by Henry Fitz & Co. and refigured in 1882 by Alvan Clark & Sons, are still in use today. Because of the importance of Fitz and Clark, two of the most noted American telescope makers of the 19th century, the Smithsonian Institution has expressed an interest in the Yeatman refractor. However, no plans exist to retire the present instrument.

Henry W. Pritchett and other Observatory astronomers made several valuable determinations of longitude. In 1905, as the University moved to the present location from downtown, the Observatory moved to a site where Louderman Hall (chemistry) now stands. In 1954, the present dome atop Crow Hall was completed.

The present observatory was constructed in 1954. Prior to its installation, the 6 inch telescope was thoroughly refurbished, and the objective was cleaned and checked at the Yerkes Observatory, under the supervision of A.B. Meinel, through the assistance of Gerard Kuiper. In January 2000, master telescope and clock craftsman Jon Slaton carried out a substantial clean-up and adjustment of the telescope mount and pointing mechanism.

The present electric drive for the telescope was installed in the mid-1960s, replacing the original pendulum drive.

The Yeatman refractor has an aperture of 6 inches, a focal length of 2,413 mm, and can magnify 60-603 times. The historic telescope, although small by present-day standards, is of excellent quality and is used to show some of the splendors of the sky to many visitors.


The 3 inch transit, by Fauth and Co. of Washington, dates from 1882, and the Howhu clock, by the Amsterdam maker, dates from 1885.

Time Service

During the latter part of the 19th century, the Observatory, at that time located at 18th and St. Charles Streets in downtown St. Louis, served as a source of standard time for the region. This time service was instituted by Richard Krom. A network of some 50,000 miles of telegraph wire existed. Henry W. Pritchett and other Observatory astronomers made several valuable determinations of longitude.

Precise checking of local time was determined by noting the Greenwich time when standard stars crossed the local meridian (the north-south line). Combining this with knowledge of the local longitude, i.e. how far the telescope was west of Greenwich, allows calculation of the precise local time.

In those days, there was no nationally-available time service, an essential requirement for a railroad system. Washington University, along with several other university observatories, operated time services which provided valuable and much-needed income. A network of some 50,000 miles of telegraph wire existed.

Standard time was adopted by the railroads in 1881. At the same time, the Western Union Telegraph Company was expanding and came to dominate the telegraph industry. It then combined with the U.S. Naval Observatory in Washington D.C., to provide a free time service. To no avail, the directors of 19 observatories signed a petition that protested this move which put their time services out of business.

Stars were observed using the 3 inch transit, by Fauth and Co. of Washington, that dates from 1882, and the clock, by the Amsterdam maker Howhu, dating from 1885. In 2003, both the clock and the transit were restored by Jon Slaton. They were displayed in Crow Hall at the special Open House celebrating the University's 150th birthday. The clock is on display in the Physics Library and the transit is in storage.