This function returns the velocity component in a given direction due to the Sun’ s motion with respect to the dynamical Local Standard of Rest. The result is $+$ve when the Sun is receding from the given point on the sky.

double palRvlsrd( double r2000, double d2000 )

r2000 = double (Given)

d2000 = double (Given)

Component of " peculiar" solar motion in direction R2000,D2000 (km/s).

• The Local Standard of Rest used here is the " dynamical" LSR, a point in the vicinity of the Sun which is in a circular orbit around the Galactic centre. The Sun’ s motion with respect to the dynamical LSR is called the " peculiar" solar motion.

• There is another type of LSR, called a " kinematical" LSR. A kinematical LSR is the mean standard of rest of specified star catalogues or stellar populations, and several slightly different kinematical LSRs are in use. The Sun’ s motion with respect to an agreed kinematical LSR is known as the " standard" solar motion. To obtain a radial velocity correction with respect to an adopted kinematical LSR use the routine palRvlsrk.

• Delhaye (1965), in " Stars and Stellar Systems" , vol 5, p73.