[LEAPSECS] leapseconds, converting between GPS time (week, second) and UTC

[Steve Allen]

On Tue 2019-01-15T11:49:00-0800 Tom Van Baak hath writ:
> Still, I bet more astronomers use Python than Excel to point
> telescopes.  How do you handle the lack of leap second support in
> Python?

I can't say that anyone uses Python to point a telescope, but it
does not matter if they do.  See preprint 678 from the 2011
Future of UTC meeting proceedings
http://hanksville.org/futureofutc/2011/preprints/index.html
In short:

19th century telescopes point by moving them manually.
20th century telescopes are built like battleships and raw pointing is
only a bit more accurate than steering a battleship.
21st century telescopes are robotic, but they still have flexure and
slop that requires them to update their pointing models regularly, and
those slop parameters easily soak up one second.

The APF telescope at Lick is robotic.  Its pointing system produces a
time mismatch alarm whenever there is a leap second and requires a
reboot.  At the most recent summer leap second we were able to see a
star before and after, and there was a jump in the centering.  The
software chose a different offset in the pointing for that night.

--
Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
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