[LEAPSECS] Ghosts of Leap-seconds past and future

[Steve Allen]

On 2010 Dec 28, at 10:33, Tony Finch wrote:

> Do practical systems get DUT1 from time broadcasts or from files downloaded from the Internet?


For the Shane 3-m telescope (built like a battleship, points like
a battleship) DUT1 is irrelevant.
For the 21st century computer-controlled subarcsecond APF 2.4-m 
telescope -- downloaded from the internet, if somebody remembers
to do it, but since the software uses Newcomb's expression for
UT even that is somewhat moot as the pointing model corrections
have to be re-done so often that they will soak up any errors.
For the downlink tracking of the X-ray timing satellites and
reduction of their orbits and onboard clocks -- that software
originated in the 1960s and still thinks that UTC = UT1.

Guidance, it's more than just a good idea.
                                                                                
--
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