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Re: Local solar time [message #39972 is a reply to message #39904]

Tue, 29 June 2004 13:19

James Kuyper
Messages: 425
Registered: March 2000

Senior Member

Craig Markwardt wrote:
> James Kuyper <kuyper@saicmodis.com> writes:
>
>> I know of at least two different things that are referred to as
>> Julian days. The first of these is indeed a time system; it is a
>> single number for every single day, starting at Jan. 1, 4713 B.C.E.
>> at 12:00:00, a time when three different cycles associated with
>> three ancient calendar systems were all synchronized. Nobody was
>> using any of those three
>
>
> James, as a mini-tutorial on julian day numbers, your post was great.
>
>
> However, I will take issue on your claim that Julian days is a "time
> system." In fact, Julian day numbers are simply a means of counting
> whole and fractional days, referred to some offset, but it is the
> definition of those days that are important!

According to the US Naval Observatory,
<http://aa.usno.navy.mil/data/docs/JulianDate.html>, Julian days are
defined in terms of Universal Time, and each one starts at Noon GMT.

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[Message index]

		Local solar time By: David Oesch on Mon, 28 June 2004 02:01
		Re: Local solar time By: David Fanning on Wed, 30 June 2004 06:29
		Re: Local solar time By: kuyper on Wed, 30 June 2004 05:59
		Re: Local solar time By: Craig Markwardt on Tue, 29 June 2004 16:36
		Re: Local solar time By: James Kuyper on Tue, 29 June 2004 13:19
		Re: Local solar time By: Craig Markwardt on Tue, 29 June 2004 12:13
		Re: Local solar time By: Craig Markwardt on Tue, 29 June 2004 11:58
		Re: Local solar time By: Craig Markwardt on Tue, 29 June 2004 11:54
		Re: Local solar time By: Michael Wallace on Tue, 29 June 2004 08:28
		Re: Local solar time By: Haje Korth on Tue, 29 June 2004 08:00
		Re: Local solar time By: Haje Korth on Tue, 29 June 2004 05:12
		Re: Local solar time By: David Oesch on Tue, 29 June 2004 05:12
		Re: Local solar time By: Haje Korth on Tue, 29 June 2004 05:09
		Re: Local solar time By: James Kuyper on Tue, 29 June 2004 04:51
		Re: Local solar time By: Craig Markwardt on Tue, 29 June 2004 02:48
		Re: Local solar time By: David Oesch on Mon, 28 June 2004 23:31
		Re: Local solar time By: Craig Markwardt on Mon, 28 June 2004 20:46
		Re: Local solar time By: Haje Korth on Mon, 28 June 2004 08:07

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