Radial velocity v_rad as a function of azimuthal position Θ measured in degrees east of north on the projected sky. Filled circles are all objects within a projected radial distance of R = 5′ to NGC 3311. Open circles are objects that deviate more than 2σ from the mean radial velocity of the sample (dashed line). The red filled squares give the mean radial velocity of the objects in bins of 45 degrees. The error bars represent the 90% confidence interval of the mean.