Name

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JDCNV

Purpose

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Converts Gregorian dates to Julian days

Explanation

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      For IDL versions V5.1 or greater, this procedure is superceded by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

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JDCNV, YR, MN, DAY, HR, JULIAN

Inputs

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  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

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JULIAN = Julian date (double precision)

Example

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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

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(1) JDCNV will accept vector arguments
(2) JULDATE is an alternate procedure to perform the same function

Revison History

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Converted to IDL from Don Yeomans Comet Ephemeris Generator,
B. Pfarr, STX, 6/15/88
Converted to IDL V5.0 W. Landsman September 1997
      Added checks on valid month, day ranges W. Landsman July 2008