Kinematic redshift
= Kinematic redshift
{title2=$1+z_{\rm kin}=\sqrt{(1+v/c)/(1-v/c)}$}
A kinematic redshift is the <relativistic Doppler effect> from relative motion of emitter and receiver. With positive radial recession speed $v$, its small-velocity limit is $z_{\rm kin}=v/c+O(v^2/c^2)$. A <peculiar velocity> gives such a factor in addition to <cosmological redshift>.