NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Leap second today
From: UNK
Date: 2012 Jul 01, 00:42 -0700
From: UNK
Date: 2012 Jul 01, 00:42 -0700
Of all answers given so far, the sibylline one given by Brad Morris that "the NA remains as accurate as it was" may come closest to the truth. Just how accurate was it?
A sufficiently diligent observer can notice that the moon has leaped forward half an arc second on July 1st when its position is recorded in UTC. Surprisingly, we cannot decide directly from information published within the NA itself whether the NA describes the observable situation more correctly for the first or for the second half of the year 2012. This offers navlist members the challenge to establish the statistical bias of the roughly 2 x 4400 moon positions in the NA with respect to the Astronomical Almnac. Alternatively, we could just ask the USNO how long in advance the NA is produced and how the prediction of delta T is handled. Probably Frank already knows the answer?
Herbert
-------- Original Message --------
Subject: [NavList] Leap second today
From: "Frank Reed" <FrankReed@HistoricalAtlas.com>
Date: Sat, June 30, 2012 10:13 am
To: NavList@fer3.com
So here's a navigational question for you to ponder: how much should the GHA of objects listed in the Nautical Almanac be adjusted after midnight UT tonight? Is your Nautical Almanac now "wrong"? Or is it always "right"?-FER----------------------------------------------------------------
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