Michael Deckers <[email protected]> wrote: > > Before the advent of atomic time keeping, clocks were less stable than > astronomical observations of Earth orientation, so that clock rates were > adjusted post factum to fit the astronomical observations at each site.
Quartz clocks can be more stable than Earth rotation: see for example http://www.ieee-uffc.org/main/history.asp?file=marrison The first outstanding application of the quartz clock to astronomy was made in Germany with the installation at the Physikalisch-Technische Reichsanstalt. This was described by Scheibe and Adelsberger in 1932 and 1934, and reports of its splendid performance continued periodically. It was with this installation that it was possible for the first time to observe and measure variations in the earth's rate occurring over intervals as short as a few weeks. Previous measurements of such variations, involving studies of motion of the moon, the planets, and Jupiter's satellites, had required years to obtain comparable information which, of course, by nature, could never reveal short-term factors. I thought this innovation was one of the reasons for moving to ephemeris time as the basis for calibrating clocks, instead relying on transit instruments. Tony. -- f.anthony.n.finch <[email protected]> http://dotat.at/ Trafalgar: North or northwest 4 or 5, occasionally 6 later. Slight or moderate. Rain or thundery showers. Moderate or good. _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
