[time-nuts] Determination of the placement of the first pps

Bob Camp lists at rtty.us
Fri Jan 20 12:30:54 EST 2012


Hi

The original location of the PPS was from astronomical data. That's still
what ultimately steers UTC. 

More precisely, for the US, there's a telescope at the Naval Observatory
that watches the sun as it comes overhead. The point it hits this or that
mark on the telescope tells you what the official solar time is (after some
math). The current one has been in place since the late 1800's, and it's
still in use. 

Bob 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bob Bownes
Sent: Friday, January 20, 2012 12:23 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Determination of the placement of the first pps

As I am, as Heinlein would say, but an egg in terms of time-nuttery,
perhaps someone could point me toward some history in order to help answer
a question recently posed to me.

At what point was the original global 1pps leading (trailing?) edge
defined/distributed and to what was (is) it referenced? Someone, someplace,
had to give the original time 'hack', no?

I found I could talk about all the wonderfullness of GPSDOs, rubidiums,
ocxo's and the like but couldn't answer that simple question with much more
depth than 'NIST does it for the US' or 'you pull it off of the GPS'.

Thanks,
Bob
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