idlastro / Astronomical Utilities: JDCNV

[Source code]

NAME
JDCNV
PURPOSE
Converts Gregorian dates to Julian days   
EXPLANATION
For IDL versions V5.1 or greater, this procedure is superceded by
JULDAY() function in the standard IDL distribution.   Note, however,
that prior to V5.1 there wasa bug in JULDAY() that gave answers off
by 0.5 days. 
CALLING SEQUENCE
JDCNV, YR, MN, DAY, HR, JULIAN
INPUTS
YR = Year, integer scalar or vector
MN = Month  integer (1-12) scalar or vector
DAY = Day   integer 1-31) scalar or vector 
HR  = Hours and fractions of hours of universal time (U.T.), scalar
      or vector
OUTPUTS
JULIAN = Julian date (double precision) 
EXAMPLE
To find the Julian Date at 1978 January 1, 0h (U.T.)
IDL> JDCNV, 1978, 1, 1, 0., JULIAN
will give JULIAN = 2443509.5
NOTES
(1) JDCNV will accept vector arguments 
(2) JULDATE is an alternate procedure to perform the same function
REVISON HISTORY
Converted to IDL from Don Yeomans Comet Ephemeris Generator,
B. Pfarr, STX, 6/15/88
Converted to IDL V5.0   W. Landsman   September 1997
dded checks on valid month, day ranges W. Landsman July 2008