[LEAPSECS] LEAPSECS Digest, Vol 172, Issue 9 TT-UT1 Changes?
Ronald Held
ronaldheld at gmail.com
Sun Nov 20 12:11:23 EST 2022
I may be missing something. Should there be any reason that TT-UT1
will change?
Ronald
On 11/20/22, leapsecs-request at leapsecond.com
<leapsecs-request at leapsecond.com> wrote:
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> Today's Topics:
>
> 1. Re: future access to solar time? (Tony Finch)
> 2. Re: Global timekeepers vote to scrap leap second by 2035
> (Steve Allen)
> 3. Re: future access to solar time?
> (Seaman, Robert Lewis - (rseaman))
> 4. Re: future access to solar time? (Kevin Birth)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 20 Nov 2022 15:15:42 +0000
> From: Tony Finch <dot at dotat.at>
> To: Leap Second Discussion List <leapsecs at leapsecond.com>
> Subject: Re: [LEAPSECS] future access to solar time?
> Message-ID: <a1902489-ea04-abcd-a14e-576e45b100ae at dotat.at>
> Content-Type: text/plain; charset=US-ASCII
>
> Seaman, Robert Lewis - (rseaman) <rseaman at arizona.edu> wrote:
>>
>> The plan, rather, is to cease easy access to solar time.
>
> The resolution says the GCPM
>
> : encourages the BIPM to work with relevant organizations to identify the
> : need for updates in the different services that disseminate the value of
> : the difference (UT1-UTC) and to ensure the correct understanding and use
> : of the new maximum value.
>
> So I think your summary is a bit off the mark.
>
> I guess the ITU is going to revise TF.460 to allow larger values of DUT1
> in time signals, and MSF etc. will accommodate the change too. (Do any of
> the national broadcast signals actually follow the ITU spec?)
>
> GPS L5 signals provide UT1 as an 8.23 bits two's complement fixed point
> difference from GPS time. This is enough to cope with the changes in the
> CGPM resolution. See IS-GPS-705 p. 87 at
> https://www.gps.gov/technical/icwg/
>
> I have not been able to find any specs for NMEA sentences that contain
> anything like UT1 or DUT1 or delta-T, but I expect they will be created
> before too long, as more GPS receivers support L5 signals.
>
> And there are other sources of UT1 like NIST's stunt NTP servers.
>
> --
> Tony Finch <dot at dotat.at> https://dotat.at/
> East Sole, Lundy, Fastnet: Westerly backing southerly, 5 to 7, then
> becoming cyclonic 7 to severe gale 9 later, perhaps storm 10 later.
> Rough or very rough, becoming very rough or high later. Rain or
> showers. Good, occasionally poor.
>
>
> ------------------------------
>
> Message: 2
> Date: Sun, 20 Nov 2022 07:49:08 -0800
> From: Steve Allen <sla at ucolick.org>
> To: Leap Second Discussion List <leapsecs at leapsecond.com>
> Subject: Re: [LEAPSECS] Global timekeepers vote to scrap leap second
> by 2035
> Message-ID: <20221120154908.GA7832 at ucolick.org>
> Content-Type: text/plain; charset=utf-8
>
> On Sun 2022-11-20T13:23:32+0000 Kevin Birth hath writ:
>> As far as I can tell, they were never successful, but it did keep them
>> busy.
>
> As Rod Serling wrote in The Big Tall Wish
> You got to believe, Bolie.
> But worse, because in this arena infidels will not be tolerated.
>
> --
> Steve Allen <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 Lng
> -122.06015
> Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m
>
>
> ------------------------------
>
> Message: 3
> Date: Sun, 20 Nov 2022 15:54:37 +0000
> From: "Seaman, Robert Lewis - (rseaman)" <rseaman at arizona.edu>
> To: Leap Second Discussion List <leapsecs at leapsecond.com>
> Subject: Re: [LEAPSECS] future access to solar time?
> Message-ID:
> <BYAPR19MB22638DE508E6B96FA8C934E6A70B9 at BYAPR19MB2263.namprd19.prod.outlook.com>
>
> Content-Type: text/plain; charset="windows-1252"
>
> Hi Tony,
>
> Getting the solar time currently means looking at your watch or the upper
> right-hand corner of the monitor. Would anybody else?s summary of the notion
> of ?easy access? include phrases like: ?8.23 bits two?s complement fixed
> point? or ?NMEA sentences that contain anything like UT1 or DUT1 or
> delta-T??
>
> I have been presuming tenth-second DUT1 values are slated for demolition
> with leap seconds. Can anybody confirm differently? I applaud the goal of
> ensuring understanding and usage of whatever infrastructure will exist. Few
> systems currently use DUT1. One of the issues is that many more will need to
> start.
>
> UT1 itself is only known retroactively. If your use of the word ?stunt?
> wasn?t a typo, it seems to me that NIST rather needs robust and easy-to-use
> infrastructure. I was never able to get reliable access to the UT1 NTP
> server, and generally, our group doesn?t build reliance on third-party NTP
> pools into our operational systems.
>
> We should all welcome GNSS support for access to UT1 (or a coherent
> variation known in advance), but as you suggest this will require new
> infrastructure and standards. Perhaps I?m off the mark, but that most
> definitely doesn?t imply anybody else has yet found the mark themselves.
>
> Rob
>
>
> Seaman, Robert Lewis - (rseaman) <rseaman at arizona.edu> wrote:
>
>> The plan, rather, is to cease easy access to solar time.
>
> The resolution says the GCPM
>
> : encourages the BIPM to work with relevant organizations to identify the
> : need for updates in the different services that disseminate the value of
> : the difference (UT1-UTC) and to ensure the correct understanding and use
> : of the new maximum value.
>
> So I think your summary is a bit off the mark.
>
> I guess the ITU is going to revise TF.460 to allow larger values of DUT1
> in time signals, and MSF etc. will accommodate the change too. (Do any of
> the national broadcast signals actually follow the ITU spec?)
>
> GPS L5 signals provide UT1 as an 8.23 bits two's complement fixed point
> difference from GPS time. This is enough to cope with the changes in the
> CGPM resolution. See IS-GPS-705 p. 87 at
> https://www.gps.gov/technical/icwg/
>
> I have not been able to find any specs for NMEA sentences that contain
> anything like UT1 or DUT1 or delta-T, but I expect they will be created
> before too long, as more GPS receivers support L5 signals.
>
> And there are other sources of UT1 like NIST's stunt NTP servers.
>
> --
> Tony Finch <dot at dotat.at> https://dotat.at/
>
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> ------------------------------
>
> Message: 4
> Date: Sun, 20 Nov 2022 16:14:55 +0000
> From: Kevin Birth <Kevin.Birth at qc.cuny.edu>
> To: Leap Second Discussion List <leapsecs at leapsecond.com>
> Subject: Re: [LEAPSECS] future access to solar time?
> Message-ID:
> <BL1PR14MB5077DB5D8DEDFDE3F2DC014BA90B9 at BL1PR14MB5077.namprd14.prod.outlook.com>
>
> Content-Type: text/plain; charset="us-ascii"
>
> As important as UT1 is in astrology, look to South Asia/East Asia for a
> solution to this problem. It is also important in the determination of
> Jewish and Islamic prayer times.
>
> Many existing apps that provide these services rely on UTC as a rough
> representation of UT1, but if UTC drifts from UT1 by more than 1 second,
> they will develop new ways to handle that difference.
>
> I expect there will be a proliferation of updated apps, some of which are
> tied to various national observatories, that will compete in the offering of
> some form of UT1 or DUT1 that could then be related to UTC on local systems.
> But given the importance of UT1 to many people, I will be curious to see if
> some nations set up their own time synchronization protocols to disseminate
> UT1. Between China and India, there's a large enough market for this.
>
> Cheers,
>
> Kevin
>
>
>
>
>
>
>
>
> ------------------
> "Time is the measure of a wobbly world, and things slipping away."
> Rabanus Maurus, 9th century.
>
> Kevin K. Birth
> Department of Anthropology
> Queens College, CUNY
> Flushing, NY 11367
> From: LEAPSECS <leapsecs-bounces at leapsecond.com> On Behalf Of Seaman, Robert
> Lewis - (rseaman)
> Sent: Sunday, November 20, 2022 10:55 AM
> To: Leap Second Discussion List <leapsecs at leapsecond.com>
> Subject: Re: [LEAPSECS] future access to solar time?
>
> Hi Tony,
>
> Getting the solar time currently means looking at your watch or the upper
> right-hand corner of the monitor. Would anybody else's summary of the notion
> of "easy access" include phrases like: "8.23 bits two's complement fixed
> point" or "NMEA sentences that contain anything like UT1 or DUT1 or
> delta-T"?
>
> I have been presuming tenth-second DUT1 values are slated for demolition
> with leap seconds. Can anybody confirm differently? I applaud the goal of
> ensuring understanding and usage of whatever infrastructure will exist. Few
> systems currently use DUT1. One of the issues is that many more will need to
> start.
>
> UT1 itself is only known retroactively. If your use of the word "stunt"
> wasn't a typo, it seems to me that NIST rather needs robust and easy-to-use
> infrastructure. I was never able to get reliable access to the UT1 NTP
> server, and generally, our group doesn't build reliance on third-party NTP
> pools into our operational systems.
>
> We should all welcome GNSS support for access to UT1 (or a coherent
> variation known in advance), but as you suggest this will require new
> infrastructure and standards. Perhaps I'm off the mark, but that most
> definitely doesn't imply anybody else has yet found the mark themselves.
>
> Rob
>
>
> Seaman, Robert Lewis - (rseaman)
> <rseaman at arizona.edu<mailto:rseaman at arizona.edu>> wrote:
>
>> The plan, rather, is to cease easy access to solar time.
>
> The resolution says the GCPM
>
> : encourages the BIPM to work with relevant organizations to identify the
> : need for updates in the different services that disseminate the value of
> : the difference (UT1-UTC) and to ensure the correct understanding and use
> : of the new maximum value.
>
> So I think your summary is a bit off the mark.
>
> I guess the ITU is going to revise TF.460 to allow larger values of DUT1
> in time signals, and MSF etc. will accommodate the change too. (Do any of
> the national broadcast signals actually follow the ITU spec?)
>
> GPS L5 signals provide UT1 as an 8.23 bits two's complement fixed point
> difference from GPS time. This is enough to cope with the changes in the
> CGPM resolution. See IS-GPS-705 p. 87 at
> https://www.gps.gov/technical/icwg/<https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.gps.gov%2Ftechnical%2Ficwg%2F&data=05%7C01%7Ckevin.birth%40qc.cuny.edu%7C0032e12a552a4f38e1e908dacb0f94e9%7C6f60f0b35f064e099715989dba8cc7d8%7C0%7C0%7C638045565490819930%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=UkI6Nr1O%2FtHAf4Hx3f32qFwzA58K6r%2B3TrK8MQL%2BCvc%3D&reserved=0>
>
> I have not been able to find any specs for NMEA sentences that contain
> anything like UT1 or DUT1 or delta-T, but I expect they will be created
> before too long, as more GPS receivers support L5 signals.
>
> And there are other sources of UT1 like NIST's stunt NTP servers.
>
> --
> Tony Finch <dot at dotat.at<mailto:dot at dotat.at>>
> https://dotat.at/<https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdotat.at%2F&data=05%7C01%7Ckevin.birth%40qc.cuny.edu%7C0032e12a552a4f38e1e908dacb0f94e9%7C6f60f0b35f064e099715989dba8cc7d8%7C0%7C0%7C638045565490819930%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=rW6Z4%2F9joFauwpFzsMmi24ULV3S8HcfEKkSC%2FAffO98%3D&reserved=0>
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