Thanks, I pushed this draft of a change:
From 614b193e524d74d0b6b616b64ec1fb58aa6a3fd2 Mon Sep 17 00:00:00 2001 From: Paul Eggert <eggert@cs.ucla.edu> Date: Mon, 2 Sep 2013 01:51:15 -0700 Subject: [PATCH] * Theory: Improve citation to Morrison & Stephenson.
Mention the 1972 UTC transition. See Steve Allen in <http://mm.icann.org/pipermail/tz/2013-September/019770.html>. --- Theory | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/Theory b/Theory index 4081b24..bd62c5c 100644 --- a/Theory +++ b/Theory @@ -240,12 +240,16 @@ locations differ in LMT. Historically, not only did different locations in the same zone typically use different LMT offsets, often different people in the same location maintained mean-time clocks that differed significantly, many people used solar or some other time -instead of mean time, and standard time often replaced LMT only gradually -at each location. As for leap seconds, we don't know the history -of earth's rotation accurately enough to map SI seconds to historical -solar time to more than about one-hour accuracy; see Stephenson FR -(2003), Historical eclipses and Earth's rotation, A&G 44: 2.22-2.27 -<http://dx.doi.org/10.1046/j.1468-4004.2003.44222.x>. +instead of mean time, and standard time often replaced LMT only +gradually at each location. As for leap seconds, civil time was not +based on atomic time before 1972, and we don't know the history of +earth's rotation accurately enough to map SI seconds to historical +solar time to more than about one-hour accuracy. See: Morrison LV, +Stephenson FR. Historical values of the Earth's clock error Delta T +and the calculation of eclipses. J Hist Astron. 2004;35:327-36 +<http://adsabs.harvard.edu/full/2004JHA....35..327M>; Historical +values of the Earth's clock error. J Hist Astron. 2005;36:339 +<http://adsabs.harvard.edu/full/2005JHA....36..339M>. As noted in the README file, the tz database is not authoritative (particularly not for pre-1970 time stamps), and it surely has errors. -- 1.8.1.2