Top-left panel: projection of the orbit of NGC 6121 in the meridional R − z plane. Colors trace time, from 5 Gyr ago (negative values) to 5 Gyr forward in time (positive values). Top-right panel: projection of the orbit of NGC 6121 in the Galactic x − y plane. Second panel: projection of the NGC 6121 orbit for the past and future 5 Gyr, in the longitude-latitude plane. Third panel: projection in the longitude-latitude plane of the extra-tidal material lost by NGC 6121. Colors indicate the average distance of the stripped material from the Sun. Bottom panel: projection in the longitude-latitude plane of the extra-tidal material lost by NGC 6121. Colors indicate the average time at which stellar particles become gravitationally unbound to the cluster, from 5 Gyr ago (negative time) to the current time (escape time = 0). In the bottom and middle panels, only the reference simulation without errors is shown for clarity. In all plots, the current position of the cluster is given by the white circle with a black outline. The yellow star, when present, indicates the position of the Sun.