local standard of rest

The local standard of rest (LSR) is the inertial reference frame matching the mean motion of Milky-Way material in the neighborhood of the Sun (solar neighborhood). When an object's radial velocity is cited, for example, the measure can be relative to the observer, which would depend upon the rotation and orbit of the Earth, or relative to the Sun, or relative to the LSR, or relative to the galactic center of the Milky Way.

The LSR velocity, i.e., the velocity of the LSR with respect to the galactic center, has a magnitude within the range of 200 to 250 km/s according to recent determinations.