[LEAPSECS] current / future state of UT1 access?

Fri Mar 16 13:50:29 EDT 2018

I regularly monitor the NIST public NTP servers including the UT1 server.
ut1-time.colorado.edu reachability was good for the past 10 weeks, though
the server was briefly in alarm on January 22 and March 10.   I can supply
details off-list.

NTP traffic is subject to Internet delay and loss that depends on the
endpoint IP addresses and often on the client UDP port.  If the client NTP
daemon (ntpd, etc.) can't contact a server, try to manually poll using
ntpdate.

This is off-topic for the Leap Seconds list, so I won't go into further
details here.

On Fri, Mar 16, 2018 at 12:18 PM, Rob Seaman <seaman at lpl.arizona.edu> wrote:

> Hi all,
>
> Regarding Demetrios's response to Steve: did astronomers give advice
> divergent to what CCIR decided? It isn't obvious how the history of this
> rather typical, if somewhat esoteric, technical debate amounts to "strong
> emotional bias". I reject the implication that technical disagreements, at
> that time or in the current day, are nothing more than emotion.
>
> It is perhaps telling that Demetrios doesn't address Steve's central
> assertion that it was recognized early on that two kinds of time were
> needed. Two kinds of time are still needed.
>
> 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
>
> Judah Levine has been very helpful in looking at things on the NIST side,
> and Harlan Stenn and Martin Burnicki have been insightful regarding NTP.
> Needless to say, this level of expert customer support is atypical! There
> is no reason to believe that NIST cannot serve UT1, and certainly such a
> brain trust (absent my fumble-fingers) could oil the gears and get the NTP
> clock spinning like a top. However, that is not currently the case from my
> campus. (We do see two other NTP servers in the same rack as that NIST UT1
> server.)
>
> I'm preparing a paper on pragmatic timekeeping for an upcoming observatory
> operations conference and would welcome comments from anybody who has been
> using the NIST's UT1 service or any other UT1 service or related internet
> tables. And those who maintain NTP instances might try connecting to
> 128.138.140.50 at the University of Colorado in Boulder and report on their
> results.
>
> For many purposes (even in astronomy) UTC currently serves as a proxy for
> UT1 and for mean solar time in general. If leap seconds cease that
> approximation will no longer be functional and the engineering requirements
> and infrastructure for delivering UT1 will be stressed manyfold. How well
> does it work now? What investment would be needed to make it reliably
> scalable? Absent emotion, what are the proposed best practices for
> providing access to the multiple timescales needed?
>
> Many thanks!
>
> Rob Seaman
> Lunar and Planetary Laboratory
> University of Arizona
> --
>
>
> 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-bounces at leapsecond.com] on behalf of Steve Allen [sla at 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                    <sla at ucolick.org> <sla at 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 <(831)%20459-3046>         Lng -122.06015
> Santa Cruz, CA 95064           http://www.ucolick.org/~sla/   Hgt +250 m
>
>
>
>
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