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Re: Julian Day Numbers
Ben Tupper <firstname.lastname@example.org> writes:
>You may have heard the proverb, 'A person with two watches
>doesn't know what time it is.' It seems to be true for me.
>I have been tinkering with making tidal predictions which,
>of course, are dependent upon time. A number of benchmark
>are used to establish the phase difference for each harmonic
>component calculated. One of the benchmark dates is Noon,
>Jan 1, 1900.
>IDL> Print, JulDay(1,1,1900,12,0,0)
Using completely independent software, I can verify that this is correct.
>However, this is just in from a reliable source...
>* From the "Explanatory Supplement to the Astronomical
>Ephemeris" 1992, p.699
>* 1900 JAN 0.5 = JD 2415020.0.
This is also correct. The date-time you used in the first calculation would be
written as "1900 JAN 1.5". There is no discrepency here, only confusion about
the notation used in the Explanatory Supplement. I would have written the date
in the above quote as "1899 DEC 31.5"