Near‐IR imaging observations of the cometary impact into Jupiter

We carried out observations of Jupiter during the impact of comet Shoemaker‐Levy 9 with Jupiter at the Okayama Astrophysical Observatory with a near‐infrared camera, OASIS. In this paper we report on result of absolute photometry of radiation from the impacts of fragment C,D and K at 2.35 µ m and discues on the impact phenomena. Lightcurve of the K impact event had four stages. We interpret the first as flash from the comet entry and the second as radiation from shock wave and/or high temperature plume itself, seen directly by Earth. The third, in which rapid increment of the infrared radiation was observed, may be caused by the increase of optical depth due to dust grain formation in the expanding and cooling plume. The fourth shows slowly decrease of the flux, which may be re‐entry phenomena of the plume.