On 2014-11-04 11:53 AM, Gerard Ashton wrote:
Of course Brooks Harris is free to define proleptic UTC any way he pleases
within the confines of a document he has control over, including a post to
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 source
code comments say "UTC began at 1960 January 1.0 (JD 2436934.5) and it is
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.
In as much as UTC
attempted to track UT2 in the 1960s, I would regard 1960 January 1.0 as the
dividing point between proleptic UTC and UTC, and I would regard proleptic
UTC as synonymous with UT2. If it turns out that creates a discontinuity at
the dividing point, so be it.
That's one of the problems with "UTC", isn't it? Everybody seems to have
a slightly different idea what it is.
-B
_______________________________________________
LEAPSECS mailing list
LEAPSECS@leapsecond.com
https://pairlist6.pair.net/mailman/listinfo/leapsecs
_______________________________________________
LEAPSECS mailing list
LEAPSECS@leapsecond.com
https://pairlist6.pair.net/mailman/listinfo/leapsecs
