[LEAPSECS] Bulletin C and all that

[Rob Seaman]

On Jan 25, 2015, at 9:57 PM, Warner Losh <imp at bsdimp.com> wrote:

>> On Jan 25, 2015, at 6:15 PM, G Ashton <ashtongj at comcast.net> wrote:
>> 
>> Rob Seaman also wrote:
>>> Leap seconds are introduced at midnight UTC, not when TAI modulo 86400 equals zero.
>> 
>> I would think that midnight UTC is the instant when the UTC time becomes
>> 00:00:00. I would call the introduced second the one that began at 11:59:60
>> and ended one second later at 00:00:00.
> 
> The second half of what Rob said is correct for at least some tens of thousands
> of years.  :). Leap seconds are introduced just before midnight UTC, and are
> properly part of the last day of the month, not the first day of the following month.
> 
> Warner

"At midnight" is a flexible enough phrase to also handle a second that *finishes* being introduced at the stroke of midnight :-)  The separation between one day and the next is a half open interval - whether on the left or the right was not the issue being discussed at the time.  In image processing coordinates might apply to the left, right or middle of the pixel.  Etc and so forth.  I defer to Steve on all issues of the historical record.

In any event I've updated the leap indexing as previously discussed.

Have also started experimenting with DUT1 encoding, which is some amalgam of the other three bulletins (predictions versus retroactive computations versus severely rounded values on uneven calendar gridding).  At any rate the 5 decimal places from Bulletin A fit neatly into a 20-bit int as at the bottom.  The idea would be to index into the entries via the explicit YYYYMM in the name.  One might imagine interpolating (linear, spline, whatever) between dates.

Rob
--

        bulletin-c.leapsec.com  ->  250.10.36.152   -> OK 2015  7  36  1  (1, 0)
            latest.leapsec.com  ->  250.10.36.152   -> OK 2015  7  36  1  (1, 0)
          previous.leapsec.com  ->  249.230.35.254  -> OK 2012  7  35  1  (1, 0)
             first.leapsec.com  ->  248.6.11.133    -> OK 1972  7  11  1  (1, 0)
            origin.leapsec.com  ->  248.0.10.245    -> OK 1972  1  10  1  (1, 0)

             leap0.leapsec.com  ->  248.0.10.245    -> OK 1972  1  10  1  (1, 0)
             leap1.leapsec.com  ->  248.6.11.133    -> OK 1972  7  11  1  (1, 0)
             leap2.leapsec.com  ->  248.12.12.208   -> OK 1973  1  12  1  (1, 0)
             leap3.leapsec.com  ->  248.24.13.158   -> OK 1974  1  13  1  (1, 0)
             leap4.leapsec.com  ->  248.36.14.76    -> OK 1975  1  14  1  (1, 0)
             leap5.leapsec.com  ->  248.48.15.2     -> OK 1976  1  15  1  (1, 0)
             leap6.leapsec.com  ->  248.60.16.129   -> OK 1977  1  16  1  (1, 0)
             leap7.leapsec.com  ->  248.72.17.6     -> OK 1978  1  17  1  (1, 0)
             leap8.leapsec.com  ->  248.84.18.147   -> OK 1979  1  18  1  (1, 0)
             leap9.leapsec.com  ->  248.96.19.154   -> OK 1980  1  19  1  (1, 0)
            leap10.leapsec.com  ->  248.114.20.85   -> OK 1981  7  20  1  (1, 0)
            leap11.leapsec.com  ->  248.126.21.129  -> OK 1982  7  21  1  (1, 0)
            leap12.leapsec.com  ->  248.138.22.40   -> OK 1983  7  22  1  (1, 0)
            leap13.leapsec.com  ->  248.162.23.128  -> OK 1985  7  23  1  (1, 0)
            leap14.leapsec.com  ->  248.192.24.127  -> OK 1988  1  24  1  (1, 0)
            leap15.leapsec.com  ->  248.216.25.124  -> OK 1990  1  25  1  (1, 0)
            leap16.leapsec.com  ->  248.228.26.174  -> OK 1991  1  26  1  (1, 0)
            leap17.leapsec.com  ->  248.246.27.9    -> OK 1992  7  27  1  (1, 0)
            leap18.leapsec.com  ->  249.2.28.21     -> OK 1993  7  28  1  (1, 0)
            leap19.leapsec.com  ->  249.14.29.193   -> OK 1994  7  29  1  (1, 0)
            leap20.leapsec.com  ->  249.32.30.45    -> OK 1996  1  30  1  (1, 0)
            leap21.leapsec.com  ->  249.50.31.138   -> OK 1997  7  31  1  (1, 0)
            leap22.leapsec.com  ->  249.68.32.220   -> OK 1999  1  32  1  (1, 0)
            leap23.leapsec.com  ->  249.152.33.233  -> OK 2006  1  33  1  (1, 0)
            leap24.leapsec.com  ->  249.188.34.161  -> OK 2009  1  34  1  (1, 0)
            leap25.leapsec.com  ->  249.230.35.254  -> OK 2012  7  35  1  (1, 0)
            leap26.leapsec.com  ->  250.10.36.152   -> OK 2015  7  36  1  (1, 0)
            leap27.leapsec.com  ->  92.242.140.2    -> CLASS ERR

       dut1.201501.leapsec.com  ->  240.210.218.53  -> -46022 -> -0.460220 seconds
       dut1.201502.leapsec.com  ->  240.198.80.149  -> -49232 -> -0.492320 seconds
       dut1.201503.leapsec.com  ->  240.184.18.42   -> -52878 -> -0.528780 seconds
       dut1.201504.leapsec.com  ->  240.166.142.108 -> -57362 -> -0.573620 seconds
       dut1.201505.leapsec.com  ->  240.150.39.208  -> -61561 -> -0.615610 seconds
       dut1.201506.leapsec.com  ->  240.137.158.247 -> -64770 -> -0.647700 seconds
       dut1.201507.leapsec.com  ->  242.10.187.39   ->  33819 ->  0.338190 seconds
       dut1.201508.leapsec.com  ->  242.9.149.181   ->  33525 ->  0.335250 seconds
       dut1.201509.leapsec.com  ->  242.2.114.186   ->  31698 ->  0.316980 seconds
       dut1.201510.leapsec.com  ->  241.245.33.186  ->  28289 ->  0.282890 seconds
       dut1.201511.leapsec.com  ->  241.227.208.63  ->  23856 ->  0.238560 seconds
       dut1.201512.leapsec.com  ->  241.213.32.100  ->  20096 ->  0.200960 seconds
       dut1.201601.leapsec.com  ->  241.201.93.90   ->  17085 ->  0.170850 seconds