Setup of our observations. The slit had a field of view of 2.5′ × 3′′ and was aligned along Jupiter’s polar axis. During the observation Jupiter had a visible diameter of about 41′. The slit was open during 50 ms, and after the exposure, the CCD charges were transferred to lower pixels, thus forming the stripe pattern image shown on the right. Each image consisted of 58 valid stripes, and we collected 208 images. For clarity, lengths in the picture are not to scale.