
On Mon, 2008-05-12 at 02:15 -0700, I wrote:
I see the problem now. TT and TAI are the same up to isomorphism, but they both can be written in YMD HMS format, with a 32.184s difference. So how to parse?
Perhaps we shouldn't at all. This is what Steve Allen has to say: http://www.ucolick.org/~sla/leapsecs/timescales.html "The forms of dynamical, atomic, and coordinate time above are not based on earth rotation. They have no connection with days in the traditional sense; thus they have no simple relationship with the concept of a calendar. It is important to remember that the 24-hour cycle of tags like 12:00:00 really only makes sense for earth rotation time." "To their credit, the BIPM do report TAI and TT using modified Julian date (MJD) notation. Nevertheless, it remains commonplace to use the traditional calendrical and sexagesimal notations when counting the seconds which are defined by these time scales. (Indeed, for the sake of human cognition this notational convenience is very nearly a requirement.) Unfortunately, that usage leads to even greater confusion about the meanings of time scales." "Denoting TAI with a tag in the form 1958-01-01T00:00:00, and denoting TT, TCG, or TCB with a tag in the form 1977-01-01T00:00:00 should be considered as a convenience only. They are merely counts of elapsed time where one anonymous and indistinguishable second follows another. It is very appropriate to count these forms of time using decimal notation from the epochs represented by those tags. But there is no observable event that happens cyclically at 12:00:00 for dynamical, atomic, or coordinate time -- the entire notion of such a cyclical process is contrary to their uniformly-incrementing conceptual definitions." -- Ashley Yakeley