palRverot palRverot - Velocity component in a given direction due to Earth rotation

Description:
Calculate the velocity component in a given direction due to Earth rotation.

The simple algorithm used assumes a spherical Earth, of a radius chosen to give results accurate to about 0.0005 km/s for observing stations at typical latitudes and heights. For applications requiring greater precision, use the routine palPvobs.


Invocation:
double palRverot ( double phi, double ra, double da, double st );

Arguments:

phi = double (Given)
latitude of observing station (geodetic) (radians)
ra = double (Given)
apparent RA (radians)
da = double (Given)
apparent Dec (radians)
st = double (Given)

Returned Value:

palRverot = double
Component of Earth rotation in direction RA,DA (km/s). The result is $+$ve when the observatory is receding from the given point on the sky.