NASA's Juno spacecraft has crossed the boundary of Jupiter's immense magnetic field. Juno's Waves instrument recorded the encounter with the bow shock over the course of about two hours on June 24, 2016.
"Bow shock" is where the supersonic solar wind is heated and slowed by Jupiter's magnetosphere. It is analogous to a sonic boom on Earth. The next day, June 25, 2016, the Waves instrument witnessed the crossing of the magnetopause. "Trapped continuum radiation" refers to waves trapped in a low-density cavity in Jupiter's magnetosphere.