The Astronomical Applications Department (AA) is one of five scientific departments within the U.S. Naval Observatory (USNO). The USNO is a U.S. Navy Echelon 4 command located organizationally under Commander Naval Meteorology and Oceanography Command (CNMOC), U.S. Fleet Forces Command (USFF), and the Chief of Naval Operations (CNO).
The AA Department mission is described elsewhere. The other scientific departments at the USNO are:
- Astrometry Department: The Astrometry Department is responsible for the determination of the positions and motions of stars and solar system objects and the establishment of celestial reference frames. Advanced equipment and methods, such as large scale CCD measuring devices, speckle and radio interferometry, are being used or developed to extend the accuracy and brightness limits of the reference frames. The results of the observational programs are published in Naval Observatory publications and in refereed journals, and are made available in electronic formats.
- Earth Orientation Department: The Earth Orientation Department determines and predicts the time-varying alignment of the Earth's terrestrial reference frame with respect to the celestial reference frame. The Earth Orientation Parameters (EOP) determined are the coordinates of the Earth's pole (polar motion), the rotation angle about the pole (Universal Time or UT1), precession, and nutation. Observational results are published regularly.
- Flagstaff Station: The Flagstaff Station is USNO's dark-sky site. Its mission is to make, analyze, and interpret such astrometric and photometric dark sky observations as are required to fulfill the mission of the U.S. Naval Observatory, and to conduct a research program to improve the observational methods and the accuracy of astronomical data required by the Navy and other components of the Department of Defense.
- Time Service Department: The Time Service Department serves as the official source of time for the Department of Defense and for the Global Positioning System (GPS), and a Standard of Time for the United States.