[LEAPSECS] The Debate over UTC and Leap Seconds

[M. Warner Losh]

In message: <20100809222912.GB8288 at ucolick.org>
            Steve Allen <sla at ucolick.org> writes:

: The Debate over UTC and Leap Seconds

: 

: is the title of a paper from the AIAA last week with contribution

: from P. Kenneth Seidelmann

: 

: It is probably the most comprehensive publicly-available paper since

: the Metrologia paper many years back.

: 

: It's available at

: http://www.agi.com/downloads/resources/user-resources/downloads/whitepapers/DebateOverUTCandLeapSeconds.pdf


A very insightful description of UT1:

	"... thereby making UT1 a very close approximation to the mean
	diurnal motion of the Sun and the best indicator of
	astronomical time of day presently maintained."

Wouldn't that also make UTC also an approximation of the mean diurnal
motion of the sun which isn't the best indicator of astronomical time
of day, but still a very good approximation?

When the law says Mean Solar Time, and there's a number of different
ways to compute a mean solar time, which mean solar time is the law of
the land?  UT1?  The noisier UT2?  UTC?  They are all approximations
of mean solar time with differing degrees of error...  Both UT1 and
UT2 have changed how they are computed over the years.  Are the laws
specific as to how the mean solar time is computed?

Warner