Examples of the annulus (the outer annulus) and the arc (the inner arc) averaging geometries. The black dot is the point where the travel time is measured. The colours correspond to the weights of the averaging geometries. The black circle delimits the artificial active region. The annulus geometry averages the quiet and the active regions because of its two-sided character; the observed point in the one-sided arc geometry is not affected by the active region. For display purposes, the radii of the averaging geometries differ, the full width at half maxima (FWHMs) of the Gaussian annuli were enlarged, and the weights of the arc geometry were divided by 12.