Rob, You miss the point. The issue is not "angle" vs. "time", but what is the "reference" clock and what is the clock, the "device", being measured. 200 years ago the reference was the earth, the device was a pendulum, a chronometer. 100 years ago, it was unclear which was measuring which. 50 years ago, the reference became atomic clock(s) and the device is now the earth.
> Then you reject Recommendation CCTF 6 (2012) I don't see how that presumption follows from a discussion about angle and time. Most of those 11 recommendations sound ok to me. Bullets 7 and 8 could use a historical footnote lest they offend old timers. Bullet 9, of which you speak, is worded a little odd and could be viewed as unnecessarily harsh or even provocative. It may not have been intended so, and does not need to be interpreted so. At least it correctly identifies UT1 as angle measurement. I don't understand why "it should not be considered" a time scale. Note that bullets 10 and 11 have no trouble subtracting "angle" and "time". UT1 could be a time scale, it was a time scale. If the plague hit the planet and we all went back to the chronometer and sextant age, it would once again be a time scale. Ok, maybe they mean it should not be considered a modern time scale. When the motivation and infrastructure of maintaining an old time scale fades away, and the old clock exists only as an accurately measured error from a new time scale, there should be a word to describe its demoted position. retired? vintage? legacy? If bullets 7, 8, 9 are worded too negatively for anyone, bullet 10 more than makes up for it. I would assume any precision astronomical system is already doing this. The accuracy with which UT1-UTC is calculated, and predicted, is amazing. You should be celebrating instead of complaining. What is missing from CCTF 6 is an honest and educational bullet 12: "systems using UT1 that assume |UT1-UTC| < 1 second may require enhancement to allow for larger than 1 second". With that, I agree and understand why you are concerned instead of celebrating. /tvb
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