A transverse quadratic version of it, known as the Shklovskii effect, is seen in pulsars. It can be used in conjunction with 
A transverse quadratic version of it, known as the Shklovskii effect, is seen in pulsars. It can be used in conjunction with the Faber-Jackson relation or the Tully-Fisher relation to estimate the distance to a galaxy. The transverse type of this effect was observed using a canal ray tube in the Ives-Stilwell experiment. Its classical formulation relates the velocity of the source, and the emitted and perceived frequencies. It is used in astronomy to measure the radial velocity of stars or galaxies, because it causes electromagnetic waves to exhibit blueshift or redshift. For 10 points, name this effect responsible for the perceived change in pitch of a moving ambulance's siren.
A transverse quadratic version of it, known as the Shklovskii effect, is seen in pulsars.
{Doppler} effect or shift