[fitsbits] Leap Second questionnaire

[Steve Allen]

On Mon 2002-06-24T16:41:23 +0000, Rob Seaman hath writ:

> Aside from the staggering change of perspective resulting from such
> a situation, much astronomical software currently assumes that UTC is
> an approximation to GMT and the cost in time and money of updating this
> software would rival, if not dwarf, the expense of Y2K to the community.

At the risk of seeming flippant, I post part of my response to IERS

Astronomical telescopes are controlled by hardware systems which tend
to have lifetimes of about 30 years.  This is the natural timescale
because the control systems are usually designed by an engineer at the
prime of his lifetime, and after implementing the system that engineer
typically cares for it until the time of his retirement.

Lick Observatory is, even now, designing the replacing its 25 year old
telescope control system.  [It uses a 6502 microprocessor.]  Any
change to the manner of operation of UTC which happens within the next
30 years will require this system to be modified.  The director of
Lick Observatory will not thank anyone who changes the way the way UTC
works and causes him to reallocate precious observatory manpower
resources before the lifetime of this new system is complete.

It makes no sense to have UTC be just another version of TAI offset
by some number of seconds.  UTC should stay the way it is.

It seems to me that any change in the way UTC works will require
international agreement.  This will take time to achieve.  The
agreement itself will have to recognize that no change can be made to
UTC without publishing the specifications of the change well in
advance.  The agreement will also have to recognize that any change to
UTC cannot occur until after some significant period of years elapses
in order to give everyone time to retire old equipment and replace it
with new systems that implement the change to the way UTC works.

I would estimate that the likely timescale for such a process is on
the order of decades, perhaps even as much as 30 years.  If that is
the case, the change to UTC will not be happening until the difference
between TAI and UTC is about one minute.  This will also occur at
about the same time as the system clocks in 32-bit Unix computers will
expire, and this will provide significant incentive for upgrading
hardware.

I propose that UTC should stay as it is.
I propose that in about 30 years, when TAI and UTC differ by
exactly one minute, that civil time be changed from UTC to TAI.
The entire world can hold a colossal leap minute party to celebrate
the event.

It's not to early to start planning that party.

--
Steve Allen          UCO/Lick Observatory       Santa Cruz, CA 95064
sla at ucolick.org      Voice: +1 831 459 3046     http://www.ucolick.org/~sla
PGP: 1024/E46978C5   F6 78 D1 10 62 94 8F 2E    49 89 0E FE 26 B4 14 93