[time-nuts] NIST UT1 NTP server results

Mike Cook michael.cook at sfr.fr
Sat Jul 23 18:05:11 EDT 2016


> Le 23 juil. 2016 à 21:56, Tom Van Baak <tvb at LeapSecond.com> a écrit :
> 
> To further clarify my question about which UTx timescale to use with NTP, or if or how to interpolate the values I've attached two plots from IERS for the past 60 days.
> 
> BTW, notice last week we had another rare moment -- where the Earth had a near perfect 86400.00000 second day!
> 
> My question is, if someone were to compare a NTP/UTC system and a NTP/UT1 system would you want the daily / weekly / monthly phase difference plot to look exactly like these IERS plots? Or do you want annual smoothing that flattens all the wonderful wiggles and wandering of the Earth's actual spin.

Interesting plots. A couple of points.
1. These look like the data points are taken at 0h and without intermediary measurements as the data points are connected by straight line segments. If we don’t know what the intermediary data points are, the plots, to my mind, should be presented « with steps ».
2. It is not beyond the abilities of IERS to determine these intermediary data points, and I expect that they already do so, or for them to disseminate them in real time.. If that were the case then any self respecting UT1 server would be able to reproduce the phase differences exactly. That is what I personally would like, but would perfectly happy in the meantime with interpolated data points. Steps aren’t good enough for reasons I previously outlined.  

> 
> In other words, are the proponents of using UT for computer timekeeping off-grid anti-atomic natural-rotation mother-earth types? Or is using UT just a way to smooth out leap seconds over an entire couple of years instead of smearing them over part of day, like what Google does.
> 
  I suppose that the answer to that depends on the objective of having a readily available accurate UT1 timescale realization. It has an intrinsic value unrelated to leap seconds so we should have it. It’s dissemination over GPS/radio would also allow the possibility of having a civil timescale without leap seconds where there would not be ‘rare moments’ of 86400 second days, but every day could have exactly 86400 seconds. 

I don’t think that proponents of having UT for a civil time scale have the characteristics that you attribute to them. Get out of bed the wrong side?

> Thanks,
> /tvb
> <iers-elod-july-2016.png><iers-dut1-july-2016.png>_______________________________________________
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