THE DIFFERENT ANSWERS ARE SEPARATED BY A LINE OF STARS Maybe polynomial parameters to predict intermediate values to an accuracy of 1ms would be a way to go, together with defined points sufficiently often to tie the polynomial down well. These might be at 10, 20, 50 or 100ms steps. ******************************************************************************* Sorry for delay. If there were to be changes, keeping TAI for frequency and other metrology use, and having time defined as under UK "1880 Statutes definition of time act" to be based on a day starting at noon, and having a variable second based on UT1 (UT2 or some other replacement) may be good, especially if the value that can be predicted at any time can be within 100us of post determined and published value; this would meet the civil need for 60s in every minute, and timepieces could be made that predict this value well, or users can continue with normal clocks and watches where the difference in value is not noticeable. Changes as far as I am concerned, for use with consumer grade GPS equipment, should not be made, or any local clock keeping should be taken as being a greater requirement for the manufacture of such equipment, and maintained locally. ******************************************************************************* I'm not a Bulletin D user. However, in general it would be useful to standardise formats and retrieval methods for bulletins (say in an RFC) and make them more friendly to automatic parsing. ******************************************************************************* Announce leap seconds for 'brackets' of, say, 5-year periods (1 to 6 years into the future). Allow the UT1-UTC tolerance to be within +/- 2 seconds. If a decision is made (under this system) for 3 leap seconds in the 5-year period concerned, but only 2 leap seconds were necessary, then subtract 1 from the prediction for the following 5-year period, in order for the 2 time-scales to converge again. If there were too few leap seconds, then put too many in the next 5-year period. This will allow some short-term certainty, while still allowing for the instability of UT1. DUT1 transmissions would need an extra tone to indicate +1 or -1 second, on top of the present CCIR DUT1 code, but I feel that, that can be accommodated fairly easily. ******************************************************************************* I don't actively use Bulletin D at the moment, but I use the estimates of future UT-TAI in the Astronomical Almanac, which I assume is related. ******************************************************************************* While I appreciate the DUT1 service,=20 I would prefer 0.01 to 0.001 sec accuracy. If the data were to improve, at a minimum the accuracy should change to 0.01 seconds. The 0.01 accuracy would reduce our positional errors from +/- 1.5 arc seconds (for 0.1 DUT1 second accuracy) to +/- 0.15 sec seconds for a side-to-side error of 0.3 arc seconds. The 0.3 arc second level is OK, but not ideal. Ideal would be have 0.001 DUT1 bulletin accuracy, if that is at all possible. This would exceed our accuracy needs. ******************************************************************************* If NO, would you prefer a more frequent and refined estimation? 0.01seconds ******************************************************************************* If NO, why? (Bulletin D has no significant impact to navigation for us.) ******************************************************************************* some other changes that might be implemented. But by that very proposal it becomes clear that the proposers are set upon making some change. Astronomical telescopes are controlled by hardware systems which tend to have lifetimes of about 30 years. This is the natural timescale because the control systems are usually designed by an engineer at the prime of his lifetime, and after implementing the system that engineer typically cares for it until the time of his retirement. UCO/Lick Observatory is, even now, designing the replacing its 25 year old telescope control system. Any change to the manner of operation of UTC which happens within the next 30 years will require this system to be modified. The director of Lick Observatory will not thank anyone who changes the way the way UTC works and causes him to reallocate precious observatory manpower resources before the lifetime of this new system is complete. 5 - Other assessment regarding determination or operation of UTC? It makes no sense to have UTC be just another version of TAI offset by some number of seconds. UTC should stay the way it is. It seems to me that any change in the way UTC works will require international agreement. This will take time to achieve. The agreement itself will have to recognize that no change can be made to UTC without publishing the specifications of the change well in advance. The agreement will also have to recognize that any change to UTC cannot occur until after some significant period of years elapses in order to give everyone time to retire old equipment and replace it with new systems that implement the change to the way UTC works. I would estimate that the likely timescale for such a process is on the order of decades, perhaps even as much as 30 years. If that is the case, the change to UTC will not be happening until the difference between TAI and UTC is about one minute. This will also occur at about the same time as the system clocks in 32-bit Unix computers will expire, and this will provide significant incentive for upgrading hardware. I propose that UTC should stay as it is. I propose that in about 30 years, when TAI and UTC differ by exactly one minute, that civil time be changed from UTC to TAI. The entire world can hold a colossal leap minute party to celebrate the event. It's not to early to start planning that party. ******************************************************************************* Comments: My answer is send once earlier On my really desk i have a HOPF DCF77, assembled of my self = - recieve every second pulses on longwave from Mainflingen and on my = wrist i wear a JUNGHANS mEGA1, as ajust 2 times ewery night at 02:00 and = You se, it is possible to me to keep controle of all my watches at every = time. On my PC i ajust the clock by calling DCF77 via the Net every time i am = online. (Tardis95 and ptb1.de)