Tuesday January 10, 2012 5:30 PM to 8:00 PM
Title:
Presenter:
Dr. Demetrios N. Matsakis.
US Naval Observatory
Abstract:
Time is the most precisely and accurately measured quantity, in the sense that
its derivative, frequency, is measured to 15 decimal points on a daily basis. This talk will
cover the timekeeping art from hardware
to software, from the technicians to the users, from local to international. Special emphasis
will be given to the activities of the U.S. Naval Observatory, whose ensemble of over 100
frequency standards includes cesium beam clocks, hydrogen masers, and rubidium atomic fountains, and
whose direct users include GPS, the Department of Defense, and perhaps your children - if they
have configured your home computer to get time from the USNO via Network Time Protocol (NTP).
Biography:
Demetrios Matsakis Ph.D.
US Naval Observatory
Demetrios Matsakis received his undergraduate degree in Physics from MIT. His PhD was from
U.C. Berkeley, and his thesis, under Charles Townes, involved building masers and using
them for molecular radio astronomy and interferometry. Hired at the US Naval Observatory (USNO)
in 1979, he measured Earth rotation and orientation using Connected Element
Interferometry and Very Long Baseline Interferometry (VLBI). Beginning in the early 90’s,
he started working on atomic clocks and in 1997 was appointed Head of the USNO’s Time
Service Department. He has over 100 publications, has served on many international commissions,
and for three years was President of the International Astronomical Union’s Commission on Time.
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