Phase coverage of spectro-interferometric observations of β Lyr acquired by different instruments. δ denotes the relative declination (positive toward the north), and α the relative right ascension (positive toward the east). The black line shows the size and orientation of the β Lyr orbit in the sky, the blue dots show orbital phases corresponding to NPOI observations, the magenta dots to CHARA/VEGA observations, the green dots to CHARA/MIRC observations acquired in 2013, and the red dots to CHARA/MIRC observations acquired in 2006/2007. An arbitrary vertical shift of 0.2 mas is added to separate the various orbits.