First observations near Jupiter by the Juno Waves investigation

The Juno spacecraft successfully entered Jupiter orbit on 5 July 2016. One of Juno's primary objectives is to explore Jupiter's polar magnetosphere for the first time. An obvious major aspect of this exploration includes remote and in-situ observations of Jupiter's auroras and the processes responsible for them. To this end, Juno carries a suite of particle, field, and remote sensing instruments. One of these instruments is a radio and plasma wave instrument called Waves, designed to detect one electric field component of waves in the frequency range of 50 Hz to 41 MHz and one magnetic field component of waves in the range of 50 Hz to 20 kHz. Juno's first perijove pass with science observations occurred on 27 August 2016. This paper presents some of the first observations of the Juno Waves instrument made during that first perijove. Among radio emissions, kilometric, hectometric, and decametric emissions were observed. From a vantage point at high latitudes, many of Jupiter's auroral radio emissions appear as V-shaped emissions in frequency-time space with vertices near the electron cyclotron frequency where the emissions intensify. In fact, we present observations suggesting Juno flew through or close to as many as five or six sources of auroral radio emissions during its first perijove. Waves made in-situ observations of plasma waves on auroral field lines such as whistler-mode hiss, a common feature of terrestrial auroral regions. We also discuss observations of dust at the equator and lightning whistlers observed over mid-latitudes.