Closure phases at λ = 1.3 mm on various triangles of VLBI stations. Different models of the orbiting spot are presented (from top to bottom) with parameters given in Table 2. Each point represents an integration time of 10 s, and the same 2 h period is shown except for the triangle including the European stations. The solid red line shows the closure phase without noise. Chile refers to the APEX telescope and Hawaii refers to 3 Hawaiian facilities phased together as described in Table 1.