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Re: timestamp resolution

From: Hans Aberg
Subject: Re: timestamp resolution
Date: Mon, 7 May 2007 19:47:46 +0200

There is a document about JD, as well other time scales, at

Apparently, JD does not take into account leap seconds (see quote below), which makes it suitable for use in distributed computer systems. If one does not like the high numbers of JD (although in 64- bit, JD seconds would be able to count more that ten times of that the currently modeled universe age), there is a MJD = JD - 2400000.5.

It does not really make sense to discuss second or smaller divisions of time scales, unless one can handle the leap second question properly. So while at it, perhaps this question should be settled as well. :-)

  Hans Aberg

Quote from link above:

It should also be noted that the use of JD or MJD for the UTC time scale is problematic and ambiguous at the precision of one second. JD and MJD express the elapsed count of some form of ``day'' as real numbers along a presumably unsegmented, continuous number line. The UTC time scale (and, historically, GMT as used in practical situations before the advent of UTC) contains changes in rate and discontinuities. In particular, there is no obvious way to represent a leap second of UTC (or the smaller leaps present in the available forms of GMT and UTC before 1972) using JD or MJD notation.

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