Temporal evolution (expressed in units of satellite revolutions) of the response loss in BP due to contamination during the period covered by Gaia EDR3. The preceding FoV is shown in black, the following FoV is shown in light blue. The very thin grey shaded areas (marked with ⋆) are the three decontamination campaigns; the two vertical purple lines (marked with ◇) are the two refocussing events; the shaded orange areas show the two time ranges that constitute the INIT period.