[LEAPSECS] nails in the coffin of mean solar time

[Tony Finch]

On Thu, 14 Jun 2007, Greg Hennessy wrote:

>

> To codify existing practice. We don't use GMT any more, we use UTC. It isn't

> even clear that with the closing of Greenwich observatory if GMT even exits.


GMT ceased to exist long before the RGO was dissolved as an organization.
The meridian marked on the ground at Greenwich is a fiction: no-one uses
it for position (not the UK Ordnance Survey, not the GPS) and it hasn't
been used for determining time since the RGO moved to Herstmonceaux.


> Well, we *don't* use mean solar time as the foundation of US civil time

> anymore. Not even USNO runs transit telescopes to take sightings of the sun.


The BBC's time signals come from a GPS receiver - not the NPL as they used
to. The UK government made a big fuss about the fact that the London
Internet Exchange is (almost) on the Greenwich meridian as part of the
millennium celebrations, to the extent of promoting (GPS-synchronized)
NTP and funding atomic clocks located at the LINX.

But our laws still say GMT.

Tony.
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f.a.n.finch  <dot at dotat.at>  http://dotat.at/
FAEROES: VARIABLE 3 OR 4. SLIGHT OR MODERATE. FAIR. GOOD.