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Abteilung Astronomie

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GET_JULDATE Source code in get_juldate.pro

GET_JULDATE

Name
    GET_JULDATE
Purpose
     Return the current Julian Date
Explanation
     This procedure became partially obsolete with the introduction of the
     /JULIAN keyword to the intrinsic SYSTIME function in IDL V5.2.   Note
     however, that SYSTIME(/JULIAN) always returns the *local* time, whereas
     for most machines, GET_JULDATE returns  Universal Time (i.e. Greenwich
     mean time.)
     In V5.4, GET_JULDATE became completely obsolete with the introduction
     of the /UTC keyword to SYSTIME().   So GET_JULDATE,jd is equivalent to
     jd = SYSTIME(/JULIAN,/UTC).
Calling Sequence
       GET_JULDATE,jd
Input Parameters
       None
Output Parameters
       jd = Current Julian Date, double precision scalar
Example
       Return the current hour, day, month and year as integers
       IDL> GET_JULDATE, JD                  ;Get current Julian date
       IDL> DAYCNV, JD, YR, MON, DAY, HOURS  ;Convert to hour,day month & year
Procedure
       The systime(1) function is used to obtain the number of days after
       1-JAN-1970.     The offset to Julian days is then computed.
       WARNING!   This procedure assumes that systime(1) returns the value
       of Universal Time (UT).    This appears to be true for most Unix
       workstations and DOS machines, but not for VMS or Macintoshes,
       for which systime(1) returns the local time.     Users
       may need to add the difference between UT and local time to the value
       of JD, depending on the particular installation.
Revision History
       Written Wayne Landsman                March, 1991
       Converted to IDL V5.0   W. Landsman   September 1997

Last modified by pro2html on 2001 April 26 at 03:11 UTC

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Jörn Wilms (wilms@astro.uni-tuebingen.de)
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