[LEAPSECS] LEAPSECS Digest, Vol 51, Issue 7

Steve Allen sla at ucolick.org
Wed Feb 2 19:31:13 EST 2011

On Thu 2011-02-03T11:14:58 +1100, Mark Calabretta hath writ:

> It's explained at p183 of "Fundamentals of astrodynamics and

> applications" by Vallado:


> http://books.google.com.au/books?id=PJLlWzMBKjkC&pg=PA183

aha, thank you, Mark, I believe this explains the origin of the code
in the telescope we bought.

Please to everyone, do not use this text when implementing anything.

It is an amalgam of expressions ranging over the entire 20th century.
The Newcomb expression is inconsistent with the FK5 system that became
valid in 1984 and invalid in 2003, and the combination usage results
in a rotation of the catalog coordinates of the entire universe.

Nevertheless, this is another example of why the name of the time
scale must change if leap seconds are not broadcast. This book, many
other books, and the professors who are teaching students with them
will all be at risk for performing calculations which use UTC as if it
were still interchangeable with UT/UT1.

Every book, student, and professor deserves to be alerted that the
broadcast time is no longer what their equations want as input.

This happened before, as noted by the IAU in 1976

Not changing the name is a mistake that should not be repeated.

Steve Allen <sla at ucolick.org> WGS-84 (GPS)
UCO/Lick Observatory Natural Sciences II, Room 165 Lat +36.99855
University of California Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m

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