[LEAPSECS] BBC radio Crowd Science

[Tom Van Baak]

>> 2017-01-01T00:00:36.5 - 36 s = 2016-12-31T23:59:60.5
>    What kind of arithmetic is that?

Hi Michael,

First, there's no problem with this, right?  (Thanks to Steve for catching typo)

2017-01-01T00:00:35.5 TAI = 2016-12-31T23:59:59.5 UTC
2017-01-01T00:00:36.5 TAI = 2016-12-31T23:59:60.5 UTC
2017-01-01T00:00:37.5 TAI = 2017-01-01T00:00:00.5 UTC

Now, we want to use "UTC = TAI + (UTC - TAI)" notation. So which is correct:

2017-01-01T00:00:35.5 TAI - 36 s = 2016-12-31T23:59:59.5 UTC
2017-01-01T00:00:36.5 TAI - 36 s = 2016-12-31T23:59:60.5 UTC  ??
2017-01-01T00:00:37.5 TAI - 37 s = 2017-01-01T00:00:00.5 UTC

or

2017-01-01T00:00:35.5 TAI - 36 s = 2016-12-31T23:59:59.5 UTC
2017-01-01T00:00:36.5 TAI - 37 s = 2016-12-31T23:59:60.5 UTC  ??
2017-01-01T00:00:37.5 TAI - 37 s = 2017-01-01T00:00:00.5 UTC

Neither one is particularly clear to me. Of course in real code it all works because you special case the leap second label discontinuity and make it work. In a sense you replace normal sexagesimal arithmetic with 59-gesimal or 61-gesimal arithmetic for that one minute. But, yeah, I can see that it complicates prose and equations regarding UTC-TAI offsets.

/tvb