Where Michigan’s History Lives


President Henry Philip Tappan opened the Detroit Observatory in 1854 with the aim of transforming a small Midwestern school into one of the first and foremost research universities in the United States. It’s hard to believe that even he could have imagined the size and scope of what U-M would become.

Throughout the decades, the Observatory was at the heart of scientific research as the first dedicated research laboratory on campus, and was home to the discovery of 21 asteroids and two comets. Listed on the National Register of Historic Places in 1973, the Observatory justifiably occupies a unique and crucial place within the storied history of the University of Michigan.


The Detroit Observatory is the oldest extant observatory in America to retain its original telescopes from the 1850s in working condition in their original mounts – notably the Fitz refracting telescope and Pistor & Martins meridian circle.

Fitz Refracting Telescope (1857)

The 12-5/8 inch objective lens of this refracting telescope was one of the largest in the world when it was completed in 1857. President Tappan ordered the telescope from Henry Fitz of New York. The original wooden telescope tube was replaced by steel in 1907. The original objective lens is unique in that it is the largest remaining Fitz lens that has not been reground. The telescope was completely restored in 1997.

Meridian Circle Telescope (1854)

Tappan ordered this 6-inch telescope from the firm of Pistor & Martins in Berlin. After the telescope was inspected by Franz Brünnow, it was shipped to New York, and then on to Ann Arbor by train. Henry Walker of Detroit donated the funds to purchase this telescope. Although antiquated by today’s standards, the meridian circle’s precision technology was used in the 19th century to determine time by tracking stars as they crossed the meridian.

Students’ Transit Telescope (1880)

This instrument, which is a small version of the meridian circle telescope, was obtained in 1880 from Fauth and Company of Washington, D.C. It was used in the Students’ Observatory, which was a separate, small building located behind the main observatory. It is currently on display in the Observatory’s museum.

Students’ Refracting Telescope (1880)

The Observatory’s director, Mark Harrington, purchased a 6-inch refractor by Alvan Clark & Sons for use in the Student’s Observatory. The Student’s Observatory was constructed because students had noted that the main telescopes were often unavailable because the faculty used them for research.

37 1/2-Inch Reflecting Telescope (1908)

In 1908, a large facility was added to the east of the Observatory that included classrooms, offices, a clock room, and a 37 1/2-inch reflecting telescope intended for spectrographic work. It was one of the largest telescopes in the world at the time, made entirely in the Observatory Shop, except for its mirror. When the addition was demolished in 1976, the massive 37 1/2-inch reflecting telescope was disassembled, but several of its parts, including the mirror and driving clock, are in storage at the University. The mount was given to the Lake Erie Astronomical Project.

Observatory Buildings

The 1854 Detroit Observatory building evolved over time, gaining a director’s residence and a large classroom addition with a new telescope. Both these additions were razed, but thanks to the efforts of many, the original building was saved and recently restored.

The building likely remained plain brick until sufficient funds were available and the brick and mortar had cured. The Observatory was stuccoed at the same time as U-M’s Medical School building in 1855. The first coat of paint was “faux stone.” Later coats of paint were flat, solid colors since the multi-step faux process was too expensive.

The second director, James Craig Watson, added a residence to house his family in 1868. The house was attached to the west side of the building, with an entrance through the director’s office.

This residence was continuously occupied by the director until 1942, when it was used as a residence for women. In 1946, it was divided into apartments for the director and members of the astronomy faculty. It was razed in 1954 to make way for the Couzens Hall dormitory expansion.

A Students’ Observatory was erected in 1878 to the south of the meridian room, during Watson’s administration, partly in response to student complaints that the Observatory’s telescopes were seldom available because the faculty used them for research. To fund the project, Watson obtained the Regents’ approval to accept an offer made by the United States Government to erect a small observatory in order to observe the transit of Mercury in May 1879.

The University later provided telescopes to replace the government’s telescopes (which had been reclaimed after Mercury observations were finished). The Student’s Observatory was moved several hundred feet to the west in 1908, then razed in 1922 to make way for Couzens Hall, a new dormitory for nurses.

By 1908, modern astronomy required a bigger and better telescope, so a large classroom building and a dome was added to the east of the building, off the meridian room.

The 1908 addition was razed in 1976, having been condemned due to termite damage. The astronomy department moved to the Dennison building in 1963, and the original Observatory building was soon derelict. The cornerstone of the 1908 addition was, however, saved, and it was incorporated into the handicap ramp’s foundation wall, which was added during the 1997-98 restoration of the building.