uv coverage (units of spatial frequency) of VLTI/PIONIER observations of Sargas. The VLTI baselines used are identified with different colors (the corresponding AT stations are indicated in the upper legend). The six points per baseline correspond to the six spectral channels of the PIONIER H band observations as described in Sect. 2.1. Projected baselines B_proj range from ∼9 to ∼132 m. A zoom of the central region is shown in the right panel, corresponding to a maximum B_proj of ∼50 m. Image adapted from the OIFits Explorer service from JMMC.