Re: What problems do leap seconds *really* create?

2003-01-30 Thread Steve Allen
On Thu 2003-01-30T00:28:57 -0800, Ken Pizzini hath writ: Right, but in its way UT1 is king because that is the measure of earth-position time which is used in the definition of our current time standard, UTC. I would go so far as to argue that UT1 is not time, but angle. UT1 does not measure

Re: What problems do leap seconds *really* create?

2003-01-30 Thread Markus Kuhn
John Cowan wrote on 2003-01-30 13:01 UTC: Markus Kuhn scripsit: Unix timestamps have always been meant to be an encoding of a best-effort approximation of UTC. Unix is in fact older than UTC. This is getting slightly off-topic, but Unix slowly evolved and was reimplemented various times

Re: Unix notion of Seconds since the Epoch

2003-01-30 Thread John Cowan
Markus Kuhn scripsit: It also provides the formula that defines the encoding of UTC into that integer, leaving no doubt about the exact semantics. I agree that this is clear, and I continue to believe that it is a regrettable and unjustified change from existing older practice, not a mere

Re: Telescope pointing and UTC

2003-01-30 Thread Markus Kuhn
Steve Allen wrote on 2003-01-30 20:17 UTC: The specifications for the automatic telescope call for an object to appear within 10 arcsec of the field center after a slew. This is congruent with what the telescope engineers can do with the flexure and hysteresis, but it obviously requires UT1

Re: Leap seconds in the European 50.0 Hz power grid

2003-01-30 Thread Steve Allen
On Thu 2003-01-30T12:54:09 +, Markus Kuhn hath writ: VERDIN phase tracking is perhaps a somewhat pathological case. True, but I know of someone who built a household clock to use it, and for someone living in a Navy base town during the early years of the Reagan era that seemed like a

Re: Leap seconds in the European 50.0 Hz power grid

2003-01-30 Thread Markus Kuhn
Steve Allen wrote on 2003-01-30 20:58 UTC: On Thu 2003-01-30T12:54:09 +, Markus Kuhn hath writ: The UCPTE specification says that the grid phase vectors have to rotate on long-term average exactly 50 * 60 * 60 * 24 times per UTC day. Obviously the grid frequency shift after leap seconds

Re: What problems do leap seconds *really* create?

2003-01-30 Thread Clive D.W. Feather
John Cowan said: Fact 2 is that the old 1980s pre-POSIX Unix manuals talked about GMT and not UTC. This strongly suggests that the authors were unfamiliar with both TAI and UTC. The seconds they refer to behave more like UT1 seconds than like TAI/SI seconds, i.e. they are Earth rotation angles

History of IEEE P1003.1 POSIX time

2003-01-30 Thread ut1-mail
As one of the main people who worked on time related aspects of the IEEE P1003.1 POSIX standard, I'd like to make a few comments about how it came to be the way it is now. First I'd like to tell you about the early consensus on time; before any of the POSIX time specs were written. I'm not

Re: Leap seconds in the European 50.0 Hz power grid

2003-01-30 Thread Steve Allen
On Thu 2003-01-30T22:05:51 +, Markus Kuhn hath writ: But the question arises as to why the spec can't easily be changed to indicate that it is per TAI day. As long as UTC is as it is currently, you don't want to do this: But I think that the further answer is this: Should it be decided

UTC, leap seconds, and the BIPM, IAU, ITU et.al.

2003-01-30 Thread Neal McBurnett
Thanks to Steve for the reference: http://danof.obspm.fr/IAU_resolutions/Resol-UAI.htm I reproduce below a resolution of more specific relevance to this discussion that was made at that meeting of the International Astronomical Union. I'm glad the IAU is looking at a wider range of options

Re: names for points in time

2003-01-30 Thread Ken Pizzini
On Fri, Jan 31, 2003 at 12:28:28AM +, [EMAIL PROTECTED] wrote: I think the historical fact that people used to treat the earth's rotation as the ultimate reference for the passage of time is not the most relevant factor in the

Re: Calabretta's 86400 s + epsilon day proposal

2003-01-30 Thread Mark Calabretta
On Thu 2003/01/30 15:39:26 -, Markus Kuhn wrote in a message to: [EMAIL PROTECTED] If you make every UTC day 86400 + epsilon(date) days long, then life gets more difficult for people who broadcast standard frequencies such as 50. Hz TV sync signals, because now you can't simply say