Detection of an Extremely Large Impact Flash on Jupiter by High-cadence Multiwavelength Observations

Abstract

We report the detection of an optical impact flash on Jupiter on 2021 October 15 by a dedicated telescope, Planetary ObservatioN Camera for Optical Transient Surveys, for the first time. Our temporally resolved three-band observations of the flash allowed investigations of its optical energy without the need for approximations on the impact brightness temperature. The kinetic energy of the impactor was equivalent to approximately two megatons of TNT, an order of magnitude greater than that of previously detected flashes on Jupiter and comparable with the Tunguska impact on Earth in 1908. This detection indicates that Tunguska-like impact events on Jupiter occur approximately once per year, two to three orders of magnitude more frequently than terrestrial impacts. The observed flash displayed a single-temperature blackbody spectrum with an effective temperature of approximately 8300 K without clear temporal variation, possibly representing common radiative features of terrestrial Tunguska-class superbolides.