On 2018-03-16 03:41 PM, Brooks Harris wrote:
On 2018-03-16 01:18 PM, Rob Seaman wrote:
Meanwhile, over the past week or two I have not been able to connect
to NIST's UT1 server:
https://www.nist.gov/pml/time-and-frequency-division/time-services/ut1-ntp-time-dissemination
My SNTP implementation reaches Judah's UT1 server today as
"ut1-time.colorado.edu"
"128.138.140.50" also successful.
-Brooks
-Brooks
On 3/16/18 9:16 AM, Matsakis, Demetrios N CIV NAVOBSY, N3TS wrote:
I was surprised to find phrases in the Lick web pages: "CCIR ignored the advice that
astronomers " and "squelched astronomers who insisted that leap seconds would cause
trouble".
I realize their author is not the only person with a strong emotional bias, but
even so I question the tone of these web pages because they are inconsistent
with the following:
1. There was a progression in thought as technology advanced and atomic clocks
proved their reliability.
2. It should be obvious that ephemeris time would need a flywheel system to get
practical time to the users, and GMT could be part of that. Today individual
labs realize UTC(k) for the same reason - to flywheel before the monthly
computations of UTC are published. WWVB, GPS, and your local cell towers are
all part of the system as well. (Even so, I think everyone today agrees that
Ephemeris time was a mistake.)
3. According to references in Nelson et al's Metrologia article, which was
peer-reviewed, it looks to me like the switch to UTC was by universal agreement among the
institutions. The IAU, URSI, CIPM(=CGPM), and CCIR(= ITU) all agreed to the current
system in the late 60's, and I would guess that the timing of their resolutions probably
depended more on the (generally) 3-year spacing of their general assemblies than anything
else. Note that many of those groups had overlapping membership. It would however be
unusual if all individual members of these bodies ever agreed to any resolution, even if
passed "by consensus".
For more trivia, the dynamic Gernot Winkler of the USNO was both a practical
clock man and astronomer. He was not the only one, and he was a very active
member of the IAU who chaired commissions, served on working groups, etc. He
told me personally that he and Essen independently came up with the idea of
leap seconds. He also said a big reason was to win the support of the
mariners, who in the pre-GNSS days actually did celestial navigation and who in
the pre-internet days could not easily get access to tables that incorporated
the difference between UT1 and UTC.
________________________________________
From: LEAPSECS [leapsecs-boun...@leapsecond.com] on behalf of Steve Allen
[s...@ucolick.org]
Sent: Wednesday, March 14, 2018 12:16 AM
To: Leap Second Discussion List
Subject: [Non-DoD Source] [LEAPSECS] D.H. Sadler in 1954
In 1954 D.H. Sadler produced a monograph on the changes in time
that had been resolved at the 1952 IAU General Assembly.
His writeup is clearer than almost anything else for the next 60 years.
It was published in Occasional Notices of the RAS, and it has been hard
to find until now.
https://www.ucolick.org/~sla/leapsecs/twokindsoftime.html
This is one of the series of documents produced starting in 1948 and
proceeding through the next 20 years where astronomers explained that
two kinds of time would be needed to satisfy all applications.
--
Steve Allen<s...@ucolick.org> WGS-84 (GPS)
UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855
1156 High Street Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m
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