Symposium on the Science of Time

The uses of time in astronomy - from pointing telescopes, coordinating and processing observations, predicting ephemerides, cultures, religious practices, history, businesses, determining Earth orientation, analyzing time-series data and in many other ways - represent a broad sample of how time is used throughout human society and in space. Time and its reciprocal, frequency, is the most accurately measurable quantity and often an important path to the frontiers of science. But the future of timekeeping is changing with the development of optical frequency standards and the resulting challenges of distributing time at ever higher precision, with the possibility of timescales based on pulsars, and with the inclusion of higher-order relativistic effects. The definition of the second will likely be changed before the end of this decade, and its realization will increase in accuracy; the definition of the day is no longer obvious. The variability of the Earth's rotation presents challenges of understanding and prediction. In this symposium speakers took a closer look at time in astronomy, other sciences, cultures, and business as a defining element of modern civilization. The symposium aimed to set the stage for future timekeeping standards, infrastructure, and engineering best practices for astronomers and the broader society. At the same time the program was cognizant of the rich history from Harrison's chronometer to today's atomic clocks and pulsar observations. The theoreticians and engineers of time were brought together with the educators and historians of science, enriching the understanding of time among both experts and the public

IAU Working Group for Numerical Standards of Fundamental Astronomy (NSFA): Past Efforts and Future Endeavors

International audienceIn 2006, the International Astronomical Union (IAU) General Assembly (GA) established the Working Group (WG) for Numerical Standards of Fundamental Astronomy (NSFA). The NSFA WG Current Best Estimates (CBEs) were adopted at the 2009 IAU GA in Resolution B2 as the IAU (2009) System of Astronomical Constants. The IAU 2012 Resolution on the re-definition of the au was proposed by the NSFA WG. Since then, the WG has concentrated on establishing the process for maintaining the CBEs in an effort to provide a service for the IAU. The NSFA web presence documents both the IAU (2009) System of Astronomical Constants and the CBEs. All old pages of the CBEs are archived in order to document history of the CBEs. The CBE policy documents the procedures established for proposal, discussion, and voting for the adoption of new CBEs. The talk reviews the efforts of the WG and provides insight into future efforts

IAU Working Group for Numerical Standards of Fundamental Astronomy (NSFA): Past Efforts and Future Endeavors

International audienceIn 2006, the International Astronomical Union (IAU) General Assembly (GA) established the Working Group (WG) for Numerical Standards of Fundamental Astronomy (NSFA). The NSFA WG Current Best Estimates (CBEs) were adopted at the 2009 IAU GA in Resolution B2 as the IAU (2009) System of Astronomical Constants. The IAU 2012 Resolution on the re-definition of the au was proposed by the NSFA WG. Since then, the WG has concentrated on establishing the process for maintaining the CBEs in an effort to provide a service for the IAU. The NSFA web presence documents both the IAU (2009) System of Astronomical Constants and the CBEs. All old pages of the CBEs are archived in order to document history of the CBEs. The CBE policy documents the procedures established for proposal, discussion, and voting for the adoption of new CBEs. The talk reviews the efforts of the WG and provides insight into future efforts

Historical Reflections on the Work of Commission 4

International audienceCommission 4 was among the first set of commissions formed within the IAU at its founding in 1919. (Commissions were originally called ``Standing Committees.'') During its 96 years of service to the IAU and astronomical community in general, the commission has been fortunate to have been led by many distinguished scientists - see the list of presidents below

HISTORICAL REFLECTIONS ON THE WORK OF COMMISSION 4

International audienceCommission 4 was among the first set of commissions formed within the IAU at its founding in 1919. (Commissions were originally called ``Standing Committees.'') During its 96 years of service to the IAU and astronomical community in general, the commission has been fortunate to have been led by many distinguished scientists - see the list of presidents below