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.help ecor Jun99 "Slalib Package"
.nf
SUBROUTINE slECOR (RM, DM, IY, ID, FD, RV, TL)
- - - - -
E C O R
- - - - -
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.
.fi
.endhelp
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