JIRAM's observations of Io during closest approaches

NASA’s Juno mission has been observing Jupiter since 2016 from a polar, highly elliptical orbit. Although not in the main scientific objectives, Juno took images and spectra of the Galilean moons from a very favourable position, using some of the cameras on board: JIRAM,  JunoCam and SRU. JIRAM, the Jovian InfraRed Auroral Mapper, is a dual-band imager and spectrometer in the infrared (2000-5000 nm); JunoCam is a visible color imager;  SRU is Juno's Stellar Reference Unit, a highly sensitive, visible  wavelength (450-1100 nm) camera.JIRAM's imager channel is a single detector with 2D capability and with 2 different filters (L band, from 3.3 to 3.6 µm; M band, from 4.5 to 5 µm). The pixel angular resolution (0.01°) is fine enough for imaging the moons from Juno; the spatial resolution at the surface of the moons varies along the s/c distance and was of the order of 100 km/pixel at the beginning of the campaign, but it's now getting better, down to ~ 500 m. Here we focus on the study of JIRAM’s high resolution images, which can characterize the location, morphology, and some temperatures, of the volcanic thermal sources; comparison with images in the visible range is also performed.