[LEAPSECS] 2 meetings on UTC and the impending ITU-R RA vote

[Tony Finch]

Michael Deckers <michael.deckers at yahoo.com> 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  <dot at dotat.at>  http://dotat.at/
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