Cloud reflection modelling for impact flashes on Jupiter: A new constraint on the bulk properties of the impact objects

We investigate optical characteristics of flashes caused by impacting meter- to decameter-sized outer solar system objects on Jupiter and contributions of reflected light from surface clouds at visible wavelengths to estimate more accurate bulk parameters such as the luminous energy of the flash, the kinetic energy, the mass, and the size of the impact object. Based on the results of recent reflectivity studies of the Jovian surface, we develop a cloud reflection model that calculates the contribution of the reflected light relative to that directly from the flash. We compare the apparent luminous energy of the previously reported flashes with the expected cloud reflection contributions to obtain their revised bulk parameters. We found that the cloud reflection contributions can be up to 200% of the flux directly from the flash and thus can be the most significant uncertainty in the measurement of the bulk parameters. The reflection contributions strongly depend on wavelength. With our cloud reflection correction, the revised bulk parameters of the previously reported flashes are obtained. Our cloud reflection correction provides a better understanding of the properties of impacting objects on Jupiter and is crucial for ongoing detailed investigations using high-sensitivity and multi-wavelength observation systems such as PONCOTS. It will also be useful for understanding other optical transients in Jupiter's upper atmosphere, such as the recently discovered sprite-like events.