[LEAPSECS] BBC radio Crowd Science

[Michael.Deckers.]

   On 2017-01-30 13:06, Tony Finch wrote:


> It's tricky. Bulletin C is pretty clear about when it thinks TAI-UTC
> changes:
>
>    from 2015 July 1, 0h UTC, to 2017 January 1 0h UTC   : UTC-TAI = - 36s
>    from 2017 January 1, 0h UTC, until further notice    : UTC-TAI = - 37s
>
    Pretty clear? Let's try. What does Bulletin C52 say about the
    relationship between UTC and TAI when TAI is equal to
    2017-01-01T00:00:36.5. Obviously, UTC - TAI at that instant
    must be either -36 s or -37 s.

    • If it is -36 s, then UTC = TAI + (UTC - TAI) = 
2017-01-01T00:00:36.5 - 36 s
      = 2017-01-01T00:00:00.5. This is > 2017-01-01, so by Bulletin C52,
      UTC - TAI = -37 s, contradiction.

    • If it is -37 s, then UTC = TAI + (UTC - TAI) = 
2017-01-01T00:00:36.5 - 37 s
      = 2016-12-31T23:59:59.5. This is < 2017-01-01, so by Bulletin C52,
      UTC - TAI = -36 s, contradiction.

    Fact is, the statement of Bulletin C52 cannot be true when the value of
    TAI is during a positive leap second, but it doesn't say so.
    So yes, pretty tricky.

    Michael Deckers.