This attribute (together with SourceVRF, RefRA, and RefDec) defines the `Source' standard of rest (see attribute StdOfRest). This is a rest frame that is moving towards the position given by RefRA and RefDec at a velocity given by SourceVel (in km/s). When setting a value for SourceVel using WCSATTRIB, the velocity should be supplied in the rest frame specified by the SourceVRF attribute. Likewise, when getting the value of SourceVel, it will be returned in the rest frame specified by the SourceVRF attribute.
The default value is zero.
KAPPA --- Kernel Application Package