Founded in 1830, the United States Naval Observatory (USNO) is among the oldest scientific agencies in the United States. Initially tasked with restoring, repairing, and rating nautical instruments, the USNO today provides precise time and celestial measurements required for GPS, telecommunications, navigation, and other operations. Intended as an introduction to the USNO, this module examines how the Observatory goes about its mission, and briefly describes the science behind its observations and publications.
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Outcome Objectives
- List the products and services of the USNO
- Describe how these products and services are used
- Describe how the USNO determines precise time
- Describe how the USNO determines earth orientation
- Define Astrometry
- List and describe the astronomical products of the USNO
Enabling Objectives
- Describe celestial, terrestrial, and GPS reference systems
- Describe UTC, UT1, GMT and the relationship between them
- Describe how precise time is used to tie reference systems
- Describe how an atomic clock works (in general terms)
- Define Astrometry
- Describe the information in a star catalog
- Define and describe VLBI
- Describe application of VLBI to EOP and plate tectonics
- List publications of the USNO
- Describe the contents of the Nautical Almanac, Air Almanac, and Astronomical Almanac
Naval Observatory, USNO, astrometry, celestial reference frame, terrestrial reference frame, Earth Orientation Parameters, EOP, Very Long Baseline Interferometry, VLBI, proper motion, parallax, double star, star catalog, Astronomical Almanac, Nautical Almanac, Air Almanac, precise time, time scale, Coordinated Universal Time, UTC, UT1, Greenwich Mean Time, GMT, International Atomic Time, TAI, atomic clock
