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Re: Converting days since 0-01-01 to Julian/Gregorian days - how can IDL recognise 0 AD? [message #89401 is a reply to message #89398]

Tue, 07 October 2014 10:29

Michael Galloy
Messages: 1114
Registered: April 2006

Senior Member

On 10/7/14, 7:21 AM, Jasdeep Anand wrote:
> I have data which has been given timestamps with the units: "days
> since 0-01-01 00:00", which I'm assuming means since January 1st, 0
> AD. I'd like to convert this into a format I can actually use,
> preferably Julian days so IDL can recognise the date format when
> plotting.
>
> From what I understand I can't use any of the default IDL programs
> for this task (JULDAY, GREG2JUL, etc) because of the fact that the
> year 0 AD doesn't exist (IDL's calendar instead goes straight from -1
> to 1 to conserve leap years).
>
> What should I do? I'm unsure of the timestamps used to calculate the
> data (all I have is the year and month) and I'll be comparing this
> with data from a separate dataset which does not have this problem. I
> don't think I can use -1 or 1 in this case as the year because the
> final Julian day will be wrong. Has anyone encountered this problem
> at all?
>
> Thanks,
>
> J. Anand
>

This is what CF conventions say about "year 0":

http://cfconventions.org/Data/cf-conventions/cf-conventions- 1.7/build/ch07s04.html

Mike
--
Michael Galloy
www.michaelgalloy.com
Modern IDL: A Guide to IDL Programming (http://modernidl.idldev.com)
Research Mathematician
Tech-X Corporation

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[Message index]

		Converting days since 0-01-01 to Julian/Gregorian days - how can IDL recognise 0 AD? By: Jasdeep Anand on Tue, 07 October 2014 06:21
		Re: Converting days since 0-01-01 to Julian/Gregorian days - how can IDL recognise 0 AD? By: Michael Galloy on Tue, 07 October 2014 10:29
		Re: Converting days since 0-01-01 to Julian/Gregorian days - how can IDL recognise 0 AD? By: Valeri Golev on Fri, 17 October 2014 03:39

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