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Even today in celestial navigation, to be strictly accurate about
time, one should really factor in the DUT correction to "broadcast
time" or UTC, to get UT1, which is time system to which the Nautical
Almanac is referenced. By the interpolation of leap seconds into UTC,
DUT is currently kept to less than 0.9 seconds, so the maximum error
will be about a quarter of a mile if this correction is not made.
This is usually neither here nor there when using a sextant to fix a
position at sea, so it is not usually accounted for, but for more
precise celestial fixes it does become a significant error.

Does it matter that DUT grows to be larger than one second? I can
hardly think that it does.

Will DUT be a difficult number to get hold of? It isn't now, I don't
see why it should be in the future. You would only really have to
acquaint oneself with the value of DUT once a year to maintain an
accuracy in time of one second.

Does the Nautical Almanac have to publish its data with reference to
UT1? Given today's computer power, it should be a trivial matter to
use broadcast time - or any other time system - as the time reference
system for its data. An equivalent of DUT could be available in the
form of a time correction to keep the ephemerides accurate to their
specified precision. Then, for all practical purposes, the status quo
would be maintained for practitioners of celestial navigation.

I think it is obvious that we need to keep to a sun based time system
so that the working day continues to be during daylight hours. But I
see no reason why it should not be a leap hour once a century or so
rather than a leap second once a year or so. After all, "summer time"
comes and goes each year without the sky falling down about our heads.

Geoffrey Kolbe

   

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