Integrated imaging spectrum of EUV-L2 observed on 1 February, 2015. Horizontal and vertical axes show wavelength (nm) and arrival direction (arcsec) of photon events, respectively. Color shows the brightness in Rayleigh/pixel in logarithmic scale. This figure plots the region of 1024 (wavelength axis) × 117 (spatial axis) pixels on the detector for good visibility. Observation targets were Jupiter’s aurora and the Io plasma torus. Spatial regions corresponding to the aurora and torus are annotated by the red arrow and curly brackets, respectively. Integration time is 677 min i.e., 677 image extensions of EUV-L2, corresponding to a 1-day observation time. Brightness in the region framed with the red broken line is reduced to the one-dimensional spectrum in Figure 11 by spatial integration. The framed region corresponds to a planeto-centric distance of 3–7 Jovian radii from Jupiter.