People intentionally throw information away, for certain purposes, even when
the information is not totally expunged. For example, when a baseball batter
ends his at-bat, the information about the number of strikes and balls
becomes irrelevant; all that matters, as far as the outcome of the game is
Rob Seaman wrote, in part, on 20 May 2015 11:27 AM
>On the other hand the thing that calendars count are mean solar days. It is
>precisely the “mean” part that permits calendars to sail unconcerned over
>daylight saving time adjustments and to ignore the red herring of the equation
>of time.
There is no RGO. There is a part of a museum named the Royal Observatory,
Greenwich.
Tony Finch wrote in part
That's because GMT (the official time promulgated by the RGO for
civil use in the UK) has been the same as UTC since 1972 or before.
_
Brooks Harris wrote on Saturday, March 7, 2015 11:50 :
.
.
"The challenge I'm trying to solve is to provide a deterministic timekeeping
and labeling scheme for date and time *after* 1972-01-01T00:00:00Z (UTC) =
1972-01-01T00:00:10 (TAI). This is essentially the purpose of "civil time"
timekeeping
A general API that deals with old dates should allow for the possibility the
original observation was stated in apparent solar time. Or, an explicit warning
should be provided that the authors of the API believed that for the intended
applications, given the limited accuracy of local time standa
Some might ask ian's question in the form "should we keep adding leap
seconds to UTC so it remains a form of mean time?" After all, it is as close
to mean time as most of the time keeping devices ordinary folks use, such as
wrist watches, PCs, and school bells.
Gerard Ashton
-Original Message
to divide
days as a statement that everyone who used the Gregorian calendar since 1582
has also divided the day at midnight.
Gerard Ashton
-Original Message-
From: Poul-Henning Kamp [mailto:p...@phk.freebsd.dk]
Sent: Monday, January 26, 2015 02:04
To: Leap Second Discussion List; G Asht
ISO 8601 defines for its purposes midnight as the start of the new day (and
end of the old day). But that does mean that since 1582 everyone who uses or
used the Gregorian calendar as their civil calendar has/had also used
midnight to divide days. Such usages may have exist, they just would not be
Brooks Harris suggested ISO 8601:2004(E), 3.2.1 "The Gregorian calendar" as
a source about the Gregorian calendar. Thanks for the suggestion, but I
consider ISO 8601 to be garbage; it's so bad it makes me dislike the entire
organization.
Gerard Ashton
Rob Seaman wrote:
>Interesting if UTC can indeed be said to have implemented two different
mechanisms whose entire point was to keep Universal Time synchronized with
Mean Solar Time.
The point of the multiple mechanisms was to keep UTC close to UT which is
mean solar time at Greenwich, or whereve
Brooks Harris mentioned, at approximately Sun 1/25/2015 21:02 UT, a
"Gregorian timescale". I believe that since in Gregory's time there was no
alternative to making the passage of calendar days agree with the day/night
cycle, we must understand "Gregorian timescale" to mean either apparent or
mean
Rob Seaman asked "Are we all agreed that it is correct to say that the
beginning of UTC is 1972-01-01T00:00:00Z with TAI-UTC 10s at that moment?"
No, that's the beginning of making UTC track UT by inserting leap seconds.
UTC existed before that, since around 1962, but the tracking mechanism was
di
Clive D. W. Feather wrote, with respect to conversion between JDN and
Gregorian calendar date,
> >So in order to calculate the
>> actual date where the drift adjustment occurs you have to face a very
> >elaborate conversion.
>No, you need to use a library that's already been written to do the jo
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