The electromagnetic coupling between the Galilean satellites at Jupiter and the planetary ionosphere generates an auroral footprint, whose ultimate source is the relative velocity between the moons and the corotating magnetospheric plasma. The footprint can be detected in the infrared L band (3.3-3.6 microns) by the Jovian InfraRed Auroral Mapper (JIRAM) onboard the Juno spacecraft, which can observe the footprint position with high precision. Here, we report the JIRAM data acquired since August 27th 2016 until May 23rd 2022, corresponding to the first 42 orbits of Juno. The dataset is used to compute the average position of the footprint tracks of Io, Europa and Ganymede. The result of the present analysis can help to test the reliability of magnetic field models, to calibrate ground-based observations and to highlight episodes of variability in the footprint positions, which in turn can point out specific conditions of the Jovian magnetospheric environment.

In this work we present the detection of CH4 and H3+ emissions in the atmosphere of Jupiter as two well separated layers, located, respectively, at a tangent altitudes of about 200 km and 500-600 km above the 1-bar level. We studied the vertical distribution of the two species retrieving their Volume Mixing Ratio (VMR) and temperature simultaneously or allowing only one quantity to vary. From this analysis, it is not possible to firmly conclude if the observed H3+ and CH4 features are due to an increase of their VMR or rather to variations of the temperature of the two molecules. However, our retrieval indicates that CH4 is in non-Local Thermal Equilibrium (non-LTE) condition, considering that the retrieved temperature values at about 300 km, where the maximum CH4 concentration lies, is always about 100 K higher than the Galileo measurements. We suggest that vertically propagating waves is the most likely explanation for the observed VMR and temperature variations in the JIRAM (Jovian InfraRed Auroral Mapper) data. Other possible phenomena could explain the observed evidences, for example a dynamical activity driving chemical species from lower layers towards the upper atmosphere, like the advection-diffusion processes responsible for the enhancement observed by Juno/MWR (MicroWave Radiometer), or soft electrons precipitation, although a better modeling is required to confirm these hypothesis. The characterization of CH4 and H3+ species, simultaneously observed by JIRAM, offers the opportunity for better constraining the atmospheric models of Jupiter and understanding the planetary formation.