palPolmo

Correct for polar motion

Description:

Polar motion: correct site longitude and latitude for polar motion and calculate azimuth difference between celestial and terrestrial poles.

Invocation

palPolmo ( double elongm, double phim, double xp, double yp, double elong, double phi, double daz );

Arguments

elongm = double (Given)
Mean logitude of the observer (radians, east +ve)
phim = double (Given)
Mean geodetic latitude of the observer (radians)
xp = double (Given)
Polar motion x-coordinate (radians)
yp = double (Given)
Polar motion y-coordinate (radians)
elong = double (Returned)
True longitude of the observer (radians, east +ve)
phi = double (Returned)
True geodetic latitude of the observer (radians)
daz = double (Returned)
Azimuth correction (terrestrial-celestial, radians)

Notes:

elong = elongm+xpcos(elongm)-ypsin(elongm) phi = phim+(xpsin(elongm)+ypcos(elongm))tan(phim) daz = -sqrt(xpxp+ypyp)cos(elongm-atan2(xp,yp))/cos(phim)

An alternative formulation for DAZ is:

x = cos(elongm)cos(phim) y = sin(elongm)cos(phim) daz = atan2(-xyp-yxp,xx+yy)