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      SUBROUTINE slECOR (RM, DM, IY, ID, FD, RV, TL)

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      E C O R
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  Component of Earth orbit velocity and heliocentric
  light time in a given direction (single precision)

  Given:
     RM,DM    real    mean RA, Dec of date (radians)
     IY       int     year
     ID       int     day in year (1 = Jan 1st)
     FD       real    fraction of day

  Returned:
     RV       real    component of Earth orbital velocity (km/sec)
     TL       real    component of heliocentric light time (sec)

  Notes:

  1  The date and time is TDB (loosely ET) in a Julian calendar
     which has been aligned to the ordinary Gregorian
     calendar for the interval 1900 March 1 to 2100 February 28.
     The year and day can be obtained by calling slCAYD or
     slCLYD.

  2  Sign convention:

     The velocity component is +ve when the Earth is receding from
     the given point on the sky.  The light time component is +ve
     when the Earth lies between the Sun and the given point on
     the sky.

  3  Accuracy:

     The velocity component is usually within 0.004 km/s of the
     correct value and is never in error by more than 0.007 km/s.
     The error in light time correction is about 0.03s at worst,
     but is usually better than 0.01s. For applications requiring
     higher accuracy, see the slEVP routine.

  Called:  slERTH, slCS2C, slVDV

  P.T.Wallace   Starlink   24 November 1994

  Copyright (C) 1995 Rutherford Appleton Laboratory
  Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.

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