Possible terminal velocities as a function of particle size. The blue hatched area shows velocities towards the negative orbital direction that would enable a particle of given size to remain in the FOV of FORS2 in August 2017. The red area indicates velocities consistent with the observed upper limit of the gas production rate according to Eq. (A5) in Jewitt et al. (2014) and for the parameters described in the text. The overlap region corresponds to combinations of size and backward ejection velocity for particles that could be expected in our image. The solid line represents the velocity-size relationship from Moreno et al. (2013) given in Eq. (6) assuming a bulk density of 1500 kg m⁻³ and v₀ = 25 m s⁻¹.