"Starting in February 2008, and continuing through July 2011, a team of European astronomers, mainly from the Observatory of Geneva and from the Centre for Astrophysics of the University of Porto, recorded measurements of Alpha Centauri B's radial velocity with European Southern Observatory's HARPS echelle spectrograph at the La Silla Observatory in Chile.The team made 459 observations of Alpha Centauri B's color spectrum over a four-year period, then used statistical filters to remove known sources of variance.