Converting Julian dates

[Brian K. White]

John Esak wrote:
> <top-posted>
>
> No offense guys... but, just how the hell would either of your
> responses as wonderfully "technical" and "correct" and "looked-up" as
> they are have helped Richard in his question about using the "Julian
> Date"??  :-)  My simple answer went one heck of a lot further toward
> being helpful than either of yours and just once, I'm going to state
> so. If the goal is helping other here, great, if it is helping one's
> own ego in who can "google up" the quickest -definition-... well, I'd
> op for the useful less *genuine* answer.
>
> Again, I say (and this time really mean...)  Sheesh!
>
> John Esak

I don't see how you can say that. Your interpretation didn't match his 
question since he quoted a value well outside the range of the day of any 
one year. In fact you provided a subset of the same help they did by 
providing one valid interpretation whereas they provided (or tried to) all 
the possible ones.

Either the question was completely false in that the data isn't actually any 
form of julian date, or the type of julian date needs to be determined 
before a formula could be proposed to interpret or generate values. And they 
tried as best as can be expected to describe the different definitions to 
help the OP answer the question.

If they hadn't "googled up" definitions, then that would be not helpful, 
leaving it up to the OP to figure out not only that there is an ambiguity to 
resolve, but also to hunt down all the possible answers, then pick the one 
trhat seems to match his data best. They tried to do as much as they could 
to just give him the legwork and let him just do the part only he can which 
is look at his data.

I can't find any fault in any of that.

Brian K. White  --  brian at aljex.com  --  http://www.aljex.com/bkw/
+++++[>+++[>+++++>+++++++<<-]<-]>>+.>.+++++.+++++++.-.[>+<---]>++.
filePro BBx  Linux SCO  Prosper/FACTS AutoCAD  #callahans Satriani


>
>> -----Original Message-----
>> From: filepro-list-bounces at lists.celestial.com
>> [mailto:filepro-list-bounces at lists.celestial.com]On Behalf Of Ron
>> Kracht Sent: Friday, November 12, 2004 8:35 PM
>> To: filePro mailing list
>> Subject: Re: Converting Julian dates
>>
>>
>> John Esak wrote:
>>
>>>>> Sounds to me like this "Julian date" is simply a count of
>>>>> days, starting at 1-Jan-1900.  Add that number to
>>>>> "12/31/1899" and you get "02/03/2004".
>>>>>
>>>>>
>>>>>
>>>> Thanks, that did it.
>>>>
>>>> Richard Kreiss
>>>>
>>>>
>>>
>>> Sheesh, did what???
>>>
>>> The julian date I know about... is the number of days from the
>> start of the
>>> year, any year.  As in
>>>
>>>   date +%j
>>>
>>>   for today gives 317
>>>
>>> Ken's question made most sense... what type of Julian value data
>>> are you talking about.  And what is this about 1-Jan-1900???
>>>
>>> John
>>>
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>>>
>>>
>>>
>> Technically a Julian date is the number of days since noon on
>> January 1, 4713 BC
>> <http://scienceworld.wolfram.com/astronomy/BC.html>.  It's called a
>> Julian date because that method of dating was first proposed by
>> Julius Scaliger in 1583.  In the computer world it seems to mean the
>> number of days since any commonly agreed upon epoch date - which is
>> why Ken asked what kind of Julian date.  Since it is originally an
>> astronomical calculation the time of day matters although for normal
>> date calculations the time of day is generally assumed to be noon -
>> resulting in whole number values when calculating the Julian date.
>>
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>
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