Re: [LEAPSECS] USNO leap seconds - a minmum-change approach

From: Brian Garrett <>
Date: Mon, 14 Aug 2000 15:11:58 -0700

----- Original Message -----
From: Seeds, Glen <Glen.Seeds_at_COGNOS.COM>
Sent: Monday, August 14, 2000 7:15 AM
Subject: [LEAPSECS] USNO leap seconds - a minmum-change approach

> Does this not resolve all objections?
> - No laws need to be changed, because these dates have already been agreed
> upon internationally as part of UTC.
> - No synchronization is lost, because the change points are precisely
> specified in advance.
> - The "civilian" requirement that UTC and UT1 never differ by more than
> seconds is preserved.
> - Software change is minimal, because UTC already includes these change
> points.
> - This will still work at 2050, because up to two seconds per year can be
> added.
> Admittedly, this will no longer be adequate when there are more than two
> seconds per year of incremental difference between UT1 and TAI. It would
> also fail should the incremental difference become negative. However,
> interim solution should give us another 100 years to work that problem
> What am I missing?
> /glen

I haven't yet commented much on this issue since I'm an interested bystander
rather than a member of the PTTI community. That being said, I want to
express my complete agreement with Glen here. This whole issue has, from
the beginning, fallen into the category of "fixing what ain't broke" from my
point of view.

Figure 3 in the article in _GPS World_ by McCarthy and Klepczynski says it
all: based on all the facts currently available, there will be *no need*
for additional leap seconds beyond those anticipated by current
international regulations and agreements until at least 2050. As I
understand those regulations and agreements, there is already a provision to
add leap seconds as needed in March or September, as well as in June and
December. This should meet the needs of the PTTI community well into the
22nd century, if I'm extrapolating that graph correctly. So why are we
discussing this now?

Brian Garrett
Received on Mon Aug 14 2000 - 15:23:14 PDT

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