[LEAPSECS] the big artillery

Joseph M Gwinn gwinn at raytheon.com
Tue Nov 4 16:20:55 EST 2014

"LEAPSECS" <leapsecs-bounces at leapsecond.com> wrote on 11/04/2014 02:45:09

> From: Brooks Harris <brooks at edlmax.com>
> To: leapsecs at leapsecond.com
> Date: 11/04/2014 02:45 PM
> Subject: Re: [LEAPSECS] the big artillery
> Sent by: "LEAPSECS" <leapsecs-bounces at leapsecond.com>
> On 2014-11-04 11:53 AM, Gerard Ashton wrote:
> > Of course Brooks Harris is free to define proleptic UTC any way he
> > within the confines of a document he has control over, including a post
> > this mailing list. But I think the term "proleptic UTC", outside the
> > confines of a document that gives it a proprietary definition, could
mean a
> > variety of things.
> Sure, thanks. But using a name that elicits incoming projectiles isn't
> so helpful either. I'll conjugate on, or accept suggestions for, a
> better name.
> > For example, the Standards of Fundamental Astronomy
> > subroutine  iauDat provides the delta between TAI and UTC, and the
> > code comments say "UTC began at 1960 January 1.0 (JD 2436934.5) and it
> > improper to call the function with an earlier date."
> For purposes of astronomy, and probably others, the "rubber band era"
> may have relevance. To call it "UTC" seems a bit of a stretch to me, but
> there's no generally accepted name for what Zefram calls "rubber-seconds
> era of UTC". Everybody has seized the name, and attempted to give it
> some meaning other than what I, at least, consider to be its origin -
> 1972-01-01T00:00:00Z, when there was exactly 10 seconds initial TAI-UTC
> offset, and when Leap Seconds were deemed to exist. As we've heard so
> often here, the term doesn't appear until sometime late in the
> development of the timescale. POSIX seized on it, NTP, PTP, and here
> another organization has extrapolated it into the past.

POSIX originally cited GMT, and changed to UTC around 1988, the reason
being simply that NIST (NBS then) had gone to UTC.

Joe Gwinn
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