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Re: two issues with julian dates [message #54815 is a reply to message #54814]

Wed, 11 July 2007 14:58

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Josh writes:

> I've got date and time strings that I've parsed into their respective
> hour/minute/etc and month/day/etc form and I'm using the julday()
> function to turn them into julian dates. I've come across two
> problems that hopefully somebody can help me with.
>
> First off, according to NASA (http://ssd.jpl.nasa.gov/tc.cgi#top), the
> returned value of julday() is incorrect. When I use 11/18/2003 at
> 16:14:43, I get 2452955.2 from IDL and 2452962.1768866 from NASA.
> Thoughts?
>
> Second, the fact that julday() only returns a value with ONE digit
> after the decimal is not cool. If it returns a double floating point
> value, shouldn't I be able to get 14 sig figs? The time scales in my
> data set are such that I need that resolution. Thoughts?

Humm. Are you using *this* IDL!

IDL> print, julday(11, 18, 2003, 16, 14, 43), format='(F 20.10)
2452962.1768865748

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: two issues with julian dates By: Josh on Thu, 12 July 2007 13:25
		Re: two issues with julian dates By: David Fanning on Thu, 12 July 2007 12:51
		Re: two issues with julian dates By: David Fanning on Thu, 12 July 2007 12:32
		Re: two issues with julian dates By: Josh on Thu, 12 July 2007 11:02
		Re: two issues with julian dates By: Jean H. on Wed, 11 July 2007 15:43
		Re: two issues with julian dates By: David Fanning on Wed, 11 July 2007 15:37
		Re: two issues with julian dates By: news.qwest.net on Wed, 11 July 2007 15:36
		Re: two issues with julian dates By: Josh on Wed, 11 July 2007 15:25
		Re: two issues with julian dates By: David Fanning on Wed, 11 July 2007 14:58
		Re: two issues with julian dates By: Josh on Mon, 16 July 2007 15:11

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