Approximate heliocentric position and velocity of the Earth
CALL sla_EARTH (IY, ID, FD, PV)
day in year (1 = Jan 1st)
fraction of day
Earth (AU, AU s-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 sla_CALYD or
The Earth heliocentric 6-vector is referred to the
FK4 mean equator and equinox of date.
Maximum/RMS errors 1950-2050:
13/5 AU = 19200/7600 km in position
47/26 AU s-1 =
0.0070/0.0039 km s-1 in speed
More accurate results are obtainable with the routine sla_EVP.