### SLA_RVEROT

RV Corrn to Earth Centre

ACTION:
Velocity component in a given direction due to Earth rotation.
CALL:
R = sla_RVEROT (PHI, RA, DA, ST)
##### GIVEN:
 PHI R geodetic latitude of observing station (radians) RA,DA R apparent $\left[\phantom{\rule{0.3em}{0ex}}\alpha ,\delta \phantom{\rule{0.3em}{0ex}}\right]$ (radians) ST R local apparent sidereal time (radians)

##### RETURNED:
 sla_RVEROT R Component of Earth rotation in direction [RA,DA] (km s${}^{-1}$)

NOTES:
(1)
Sign convention: the result is positive when the observatory is receding from the given point on the sky.
(2)
Accuracy: the simple algorithm used assumes a spherical Earth and an observing station at sea level; for actual observing sites, the error is unlikely to be greater than 0.0005 km s${}^{-1}$. For applications requiring greater accuracy, use the routine sla_PVOBS.