Celestial Reference Frame Department History

The Astrometry Department has existed in various forms since the 19th century. For much of its history its main concern has been the operation of transit circles. In the late 1950's two departments, the six-inch transit circle and the seven-inch transit circle divisions, were responsible for the operation of the two instruments and the data analysis and production of the observational catalogs. The Equatorial Division operated the 26- inch refractor, mostly for double star research. In 1969 the seven- inch transit circle was sent to El Leoncito, Argentina to observe the southern component of the International Reference Stars, the SRS.

The six-inch transit circle observed the northern component of the IRS, the AGK3. At the time the names of the divisions were changed to Northern and Southern Transit Circle Divisions. In 1977 the seven-inch transit circle was returned to Washington where an image dissector micrometer system was developed and installed. The two Divisions were combined with the Equatorial Division to produce the Astrometry Department.

The seven-inch transit circle was sent to Black Birch, New Zealand, to observe the second epoch of the SRS, while the six-inch transit circle observed the IRS in the North. An 8-inch twin (yellow and blue lens) astrograph was acquired and sent to Black Birch to photograph the southern sky. These projects ended in 1995 and the seven-inch transit circle was removed from Black Birch and placed in storage in Washington. The six-inch transit circle remains operational (and celebrated 100 years of operation in 1997 with a brief set of measurements made by T. Rafferty), but the successful operation of the European Hipparcos satellite effectively obsoleted the transit circles.

In 1997 the astrograph mentioned above was fitted with a new "red" lens and a 4kx4k CCD camera and sent to Cerro Tololo, Chile to begin a program of observing the southern sky to unprecedented accuracy from the ground.

6-inch Transit Circle

Director Tenure from Tenure to
J. C. Hammond 1911 1933
C. B. Watts 1934 1959
A. Norwood Adams 1959 1969
Benny L. Klock 1970 1976*

* see Transit Circle Division below.

9-inch Transit Circle

Director Tenure from Tenure to
A. N. Skinner 1894 1900
F. B. Littell 1901 1903
W. S. Eichelberger 1903 1908
F. B. Littell 1908 1913
H. R. Morgan 1913 1944**

** the 9-inch Transit Circle Division was decommissioned at Morgan's retirement in 1944

7-inch Transit Circle

Director Tenure from Tenure to
Francis P. Scott 1948 1970
Jack L. Schombert 1970 1976***

*** see Transit Circle Division below

 In 1977 the transit circle instruments were placed under a single Transit Circle Division.

Transit Circle Division

Director Tenure from Tenure to
Jack L. Schombert 1976 1977
James A. Hughes 1977 1982

In 1982 the Transit Circle Division became the Astrometry Department.

Astrometry Department

Director Tenure from Tenure to
James Hughes 1982 1992
F. Stephen Gauss 1993 2000
Theodore J. Rafferty 2000 2002
Ralph A. Gaume 2002 2014
Bryan Dorland 2014 2020

In 2020 the Astrometry Department and NOFS were combined into the Celestial Reference Frame Department.

Naval Observatory Flagstaff Station (NOFS)

Director Tenure from Tenure to
Arthur Hoag 1955 1965
Gerald E. Kron 1965 1973
Harold Ables 1974 1995
Conard Dahn 1996 2003
Jeff Pier 2003 2008
Paul Shankland 2008 2020
Michael DiVittorio 2020 Present

Celestial Reference Frame Department

Director Tenure from Tenure to
Bryan Dorland 2020 Present