SEAN E. URBAN is Chief of the Nautical Almanac Office of the US Naval Observatory and a member of the American Astronomical Society, the Division of Dynamical Astronomy, and the International Astronomical Union's Division I (Fundamental Astronomy), Commission 4 (Ephemerides), and Commission 8 (Astrometry). In 1985, he was hired as a staff astronomer in the Astrometry Department of the US Naval Observatory, where he eventually rose to Chief of the Cataloging and Requirements Division. He has authored or co-authored over 70 articles, most on positional astronomy.
P. KENNETH SEIDELMANN is a Research Professor at the University of Virginia, USA and previously held the post of director of Astronomy at the US Naval Observatory. His recent work has focused on space astrometry missions, Origins Billion Star Survey (OBSS), Astrometric Mapping Explorer (AMEX), and the Full-sky Astrometric Mapping Explorer (FAME). He is Chair of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements and the Celestial Mechanics Institute.
