Depth of the differential visibility curves for Rigel referenced to the uniform-disk diameter curve, corresponding to 2.76 mas. The AMBER measurements of the differential visibility obtained in the core of the line are indicated by triangles (2006−2007 campaign) and squares (2009−2010 campaign). A fit of theses values by two uniform-disk diameter curves provides with angular diameters of 3.58 ± 0.04 mas and 3.45 ± 0.04 mas, for 2006−2007 and 2009−2010, respectively.