[LEAPSECS] Common Calendar Time (CCT) -Brooks Harris

[Brooks Harris]

On 2014-01-17 10:49 PM, Ian Batten wrote:

> On 18 Jan 2014, at 01:22, Zefram <zefram at fysh.org> wrote:

>

>> Brooks Harris wrote:

>>> Yes, I understand that. Perhaps using the word "origin" was careless.

>>> Maybe you can suggest a better term.

>> "proleptic".  You may usefully add "with astronomical year numbering" to

>> make clear that zero and negative year numbers are valid.  But really,

>> when you're defining a time scale, the calendar is irrelevant.  It's a

>> separate concern that should be addressed separately.

>>

>>> Of course the idea is that dates after 1972-01-01T00:00:00Z are

>>> "earth corrected" (Leap Seconds).

>> Are you implying that dates before are not?  That wouldn't be a proleptic

>> UTC.

> Can someone suggest an application for a proleptic UTC representing dates in the distant past

> such that the differences between it and, say, proleptic UT1, proleptic TAI or proleptic GPS

> time would be significant, and where the issues would be common to some other application?

> Outside the production of historical astronomical data, where I suspect they are going to

> want a timescale which reflects variations in day length anyway, it's hard to think of

> applications where the recorded timestamps have precision better than the differences between

> these various putative timescales.

>

>

The purpose of the timescale I've suggested is accurate time-keeping 
after 1972. The "proleptic UTC" (and it may need a different name) I've 
tried to describe is an artificial construction for computational 
convenience with defined relation to NTP, POSIX, and 1588/PTP. Its not 
intended to be accurate before 1972.

On the other hand, a proleptic UTC with adjustments into the deep past 
might be useful for, say, nit-picking historians, maybe the carbon 
dating crowd. Interesting, but I wasn't trying to solve such problems, 
if they exist.

-Brooks