[LEAPSECS] LEAPSECS Digest, Vol 51, Issue 8

[Finkleman, Dave]

I like these.  

With regard to terminology, there are at least three "normative"
definitions of the second among ISO standards.  8601, Data Exchange
Formats, sanctions everything under the Sun.  Maybe everything in the
Universe.  ISO 31-1 states that "second" without qualification is the SI
second.  It does not recognize any other kind of second.  Other ISO
documents define minutes, etc., in terms of unqualified seconds -- by
implication, SI seconds.  One even defines a second as 1/60th of a
minute.  It is all over the map.  I am working this through ISO, but it
is painful.  It boils down to "what difference does it make to me?"  The
fallacy is that standards are not developed for people who don't need
them.  They are developed for people who do need them, but that
constituency is never well represented among the governing authorities.

I will forward the consensus list to colleagues in ISO terminology, who
have been forthcoming and force a productive outcome.   If it gets too
heavy, we can always throw in PHK!

Dave Finkleman
Senior Scientist
Center for Space Standards and Innovation
Analytical Graphics, Inc.
7150 Campus Drive
Colorado Springs, CO 80920
 
Phone:  719-510-8282 or 719-321-4780
Fax:  719-573-9079
 
Discover CSSI data downloads, technical webinars, publications, and
outreach events at www.CenterForSpace.com.

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Subject: LEAPSECS Digest, Vol 51, Issue 8

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Today's Topics:

   1. Re: Consensus building? (Rob Seaman)
   2. Re: LEAPSECS Digest, Vol 51, Issue 7 (Finkleman, Dave)
   3. Re: Consensus building? (Rob Seaman)
   4. Re: LEAPSECS Digest, Vol 51, Issue 7 (Stephen Colebourne)
   5. Re: Consensus building? (Stephen Colebourne)


----------------------------------------------------------------------

Message: 1
Date: Wed, 2 Feb 2011 07:24:44 -0700
From: Rob Seaman <seaman at noao.edu>
Subject: Re: [LEAPSECS] Consensus building?
To: Leap Second Discussion List <leapsecs at leapsecond.com>
Message-ID: <26C3DB78-9873-4863-8447-63B152A7C0A5 at noao.edu>
Content-Type: text/plain; charset=us-ascii

Stephen Colebourne wrote:


> This list is good at disagreeing, but given the brainpower here,

perhaps some consensus building might be good? I'll try one approach,
and see what happens.

This is a good "creative problem solving" exercise.  We tried various
other approaches back in the day:

	http://www.ucolick.org/~sla/navyls

If folks (on all sides - we have many more than two here) can relax
their guard a bit, the exercise may pay off, perhaps surprisingly so.
Note that the pay off is most likely to reveal itself in issues around
the periphery.  This isn't all-or-nothing.

As facilitator, Stephen will need the patience of Job.

I'll personally refrain from comment for a few rounds.  My only
suggestion at this point is that declarative statements should be kept
as brief as possible.  Avoid subordinate clauses and conditionals,
rather divide complex assertions into separate simple statements.  You
might consider a glossary.

Rob



------------------------------

Message: 2
Date: Wed, 2 Feb 2011 10:33:55 -0500
From: "Finkleman, Dave" <dfinkleman at agi.com>
Subject: Re: [LEAPSECS] LEAPSECS Digest, Vol 51, Issue 7
To: <leapsecs at leapsecond.com>
Message-ID: <3B33E89C51D2DE44BE2F0C757C656C880A1366E7 at mail02.stk.com>
Content-Type: text/plain;	charset="us-ascii"

The consensus list of facts is an excellent idea.  I wish the US could
do this with health care: implement what everyone can agree with and
debate the rest instead of holding everything hostage to winning a minor
point.

I suggest that the terms second, minute, hour, day, and month stated
without qualification have "normative" status:  the SI second, 60 SI
seconds, 3600 SI seconds, 86,400 SI seconds, and Gregorian calendar
numbers of days expressed as 86,400 seconds.

Anything else requires qualification such as: mean solar seconds.
Actually I can't think of other forms of hour, day, etc. that require
qualification, since those are neither fundamental time intervals nor
time scales.

An initial thought for discussion.

Dave Finkleman
Senior Scientist
Center for Space Standards and Innovation
Analytical Graphics, Inc.
7150 Campus Drive
Colorado Springs, CO 80920
 
Phone:  719-510-8282 or 719-321-4780
Fax:  719-573-9079
 
Discover CSSI data downloads, technical webinars, publications, and
outreach events at www.CenterForSpace.com.



------------------------------

Message: 3
Date: Wed, 2 Feb 2011 08:57:32 -0700
From: Rob Seaman <seaman at noao.edu>
Subject: Re: [LEAPSECS] Consensus building?
To: Leap Second Discussion List <leapsecs at leapsecond.com>
Message-ID: <5DBB6F0C-DB6A-41FF-B930-558518EC418C at noao.edu>
Content-Type: text/plain; charset=us-ascii

Um - as I said I will refrain from comment on the assertions.  However,
I also said a glossary might be a good idea.  The "SI second" is a well
defined concept.  These others certainly have no normative force.  In
particular, the essence of the problem in front of us is that the
Gregorian calendar does not count something called "SI days".  Since the
exercise is to build as much consensus as possible, we might most
productively avoid strong assertions about points in dispute.

Regarding vocabulary, I'd suggest that fully qualified terms will raise
the fewest hackles.  For instance, "SI second" has a very clear meaning,
but "second" is ambiguous (and will remain so no matter what action is
taken).

Rob
--

On Feb 2, 2011, at 8:33 AM, Finkleman, Dave wrote:


> I suggest that the terms second, minute, hour, day, and month stated

> without qualification have "normative" status:  the SI second, 60 SI

> seconds, 3600 SI seconds, 86,400 SI seconds, and Gregorian calendar

> numbers of days expressed as 86,400 seconds.

> 

> Anything else requires qualification such as: mean solar seconds.

> Actually I can't think of other forms of hour, day, etc. that require

> qualification, since those are neither fundamental time intervals nor

> time scales.




------------------------------

Message: 4
Date: Wed, 2 Feb 2011 16:03:51 +0000
From: Stephen Colebourne <scolebourne at joda.org>
Subject: Re: [LEAPSECS] LEAPSECS Digest, Vol 51, Issue 7
To: Leap Second Discussion List <leapsecs at leapsecond.com>
Message-ID:
	<AANLkTinA9QoR5eAW+cj2_L_V7K9kOahV=RSFZhJ1zgua at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

On 2 February 2011 15:33, Finkleman, Dave <dfinkleman at agi.com> wrote:

> I suggest that the terms second, minute, hour, day, and month stated

> without qualification have "normative" status: ?the SI second, 60 SI

> seconds, 3600 SI seconds, 86,400 SI seconds, and Gregorian calendar

> numbers of days expressed as 86,400 seconds.


Funilly enough, I'll start by disagreeing with those definitions. The
meaning of the things named "second" and "day" being key, the best
that consensus will agree to is precise definitions, rather than any
"land grab" of key terms.

The terms SI-based-minute, SI-based-hour and SI-based-day will, I
suspect be acceptable to all. At the end of the process, the
defniition of the simple terms can then be considered.

Statements:
- an SI-based-minute is formed from exactly 60 SI-seconds
- an SI-based-hour is formed from exactly 60 SI-based-minutes and thus
exactly 3600 SI-seconds
- an SI-based-day is formed from exactly 24 SI-based-hours and thus
exactly 86400 SI-seconds


> Anything else requires qualification such as: mean solar seconds.

> Actually I can't think of other forms of hour, day, etc. that require

> qualification, since those are neither fundamental time intervals nor

> time scales.


Defining things that are *not*  fundamental time intervals nor time
scales is key to the problem.

I'll resend in the main thread an updated list so far.

Stephen


------------------------------

Message: 5
Date: Wed, 2 Feb 2011 16:47:22 +0000
From: Stephen Colebourne <scolebourne at joda.org>
Subject: Re: [LEAPSECS] Consensus building?
To: Leap Second Discussion List <leapsecs at leapsecond.com>
Message-ID:
	<AANLkTinUEZNcnnCESKbMsJt99hTBGS9WY-dZg7FO8Wn0 at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Statements so far - disgree or add please (in particular something on
UT1/UT/etc as I will only get it wrong...):

General:
- the terms seconds, minutes, hours and days are overloaded, thus
pedantic and explicit terms are used here

SI
- the SI-second is a standardised unit of measurement
- the SI-second is currently defined as a fixed number of transitions
of a caesium atom
- the current definition of the SI-second was ratified in 1967
- an SI-based-minute is formed from exactly 60 SI-seconds
- an SI-based-hour is formed from exactly 60 SI-based-minutes and thus
exactly 3600 SI-seconds
- an SI-based-day is formed from exactly 24 SI-based-hours and thus
exactly 86400 SI-seconds

Solar
- a solar-day is a measured period of time
- the length of a solar day in in SI-seconds varies over time
- the length of a solar day in in SI-seconds is on average increasing
with time
- a solar day is not a fixed number of SI-seconds
- a solar-hour is the period of 1/24th of a single measured solar-day
- a solar-minute is the period of 1/60th of a solar-hour and thus
1/1440th of a single measured solar-day
- a solar-second is the period of 1/60th of a solar-minute and thus
1/86400th of a single measured solar-day

Humanity
- a humanity-day is a non-scientific, commonly used term understood by
6bn humans
- a humanity-day is interpreted in line with the rising and setting of
the Sun

TAI-2011
- the TAI-2011 time-scale is known as TAI in the year 2011
- the TAI-2011 time-scale is defined as a uniformly increasing count
of SI-seconds from a fixed epoch

UT-2011
???

UT1-2011
???

UTC-2011
- the UTC-2011 time-scale is known as UTC in the year 2011
- the UTC-2011 time-scale is a continuous count of SI-seconds
- the UTC-2011 time-scale defines UTC-2011-days
- a UTC-2011-day is either 86400 SI-seconds or 86401 SI-seconds long
- the additional SI-second in a UTC-2011-day is a leap-second
- the presence or absence of a leap-second is determined up to 6
months in advance


Lets see, how we go on these...

Stephen


------------------------------

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