pro get_juldate,jd ;+ ; 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.) ; ; CALLING SEQUENCE: ; GET_JULDATE,jd ; ; INPUTS: ; None ; ; OUTPUTS: ; 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 ; ; METHOD: ; 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 ;- if N_Params() LT 1 then begin Print,'Syntax - GET_JULDATE, JD' return endif x = systime(1) ;Number of seconds elapsed since 1-jan-1970 days = x/24./3600. ;Number of days elapsed since 1-jan-1970 jd0 = 2440587.5d ;Julian Date of 1-jan-1970 jd = jd0 + days ;Return current Julian date end