Geometric error for triangulating a single-point object as a function of spacecraft separation angle. The object is observed by two separated spacecraft: the Solar Orbiter and one Earth-orbiting spacecraft (SDO, Hinode, or IRIS). The separation angles between the Earth-Sun line and the Solar Orbiter–Sun line varies over the whole range of angles during the cruise and nominal phase of the mission. Angles of ±90° provide the minimal triangulation error of 1.4 pixels for the 3D geometry reconstruction using Solar Orbiter high-resolution imagers HRI_EUV and HRI_Lya. Separation angles greater than 100° between the spacecraft can complicate pointing at the same area of the Sun with two spectrometers and is therefore not recommended. However, the angle interval of 10° −100° provides a sufficiently small triangulation error and good pointing possibilities for spectrometers.