11.5.1. Position Profiles
An interferometer with a multi-channel receiver is an inherently powerful tool for line observations, because the phase in each velocity channel contains information about the position of the source of radiation received in that velocity interval. A phase relationship over several channels can confirm a detection of a weak signal, while for stronger signals the phase gives the relative position in the sky of radiation received in each velocity channel. A plot of position versus velocity is often called a position profile.