English: On October 24, 2017, NASA's Juno probe successfully performed her Perijove-09 Jupiter flyby. At that time, Jupiter was close to solar conjunction with respect to Earth. This means, that the sun was between Jupiter and Earth, and blocked reliabale communication. Jupiter was also hidden for Earth-based observations. So JunoCam, Juno's Education and Outreach camera, took images without detailed knowledge of which features to expect within its field of view during Jupiter flyby. Fortunately, JunoCam's assigned memory has been incremented, such that JunoCam was able to cover all latitudes with close-up images. The movie is a reconstruction of the flyby in 125-fold time-lapse, based on the JunoCam images taken, and based on spacecraft trajectory data provided via SPICE kernel files. In more detail, the 20 Perijove-09 RGB images #75, #76, #78 to #85, #88 to #95, #97, and #98 went into this animation. In steps of five real-time seconds, one still images of the movie has been rendered from at least one suitable raw image. This resulted in short scenes, usually of a few seconds. Playing with 25 images per second results in 125-fold time-lapse. Resulting overlapping scenes have been blended using the ffmpeg tool. In natural colors, Jupiter looks pretty pale. Therefore, the still images are approximately illumination-adusted, i.e. almost flattened, and consecutively gamma-stretched to the 4th power of radiometric values, in order to enhance contrast and color.

The movie starts with a resonstructed in-bound sequence approaching Jupiter from north. Then the orbit approaches Jupiter down to an altitude of between 3,000 and 4,000 km near the equator. This is followed by a transition into the outbound orbit, during which Jupiter's south polar region comes into the view. The movie covers two real-time hours. Rendering the still images of the movie took about three days on three virtual CPU cores running in parallel. The rendering software for the stills is proprietary. Trajectory data were retrieved from SPICE kernels with the SPICE/NAIF tool spy.exe. For combining stills to movie files, the tool ffmpeg has been used. Blending may result in feature-doubling in overlapping scenes due to reprojection inaccuracies. Most repetitive bright and dark camera artifacts are patched. Due to the intense radiation near Jupiter, several additional bright pixels occured. Those aren't patched in this animation. In rarer cases, lightnings on Jupiter may also show up as bright pixels.

Some of the close-ups show perceptable macro blocks. Those are effects of lossy data compression, which is necessary in order to store a reasonable number of images in the limited on-bord memory of the spacecraft, especially during solar conjunction when no data can be transmitted to Earth before, and during the perijove pass. Sometimes, the edges of the raw images show up as black triangular areas in some corners of the movie rendition. During blending, features may be doubled due to alignment inaccuracies of the blended scenes. The sometimes very bright limb is an effect of inaccuraties of the applied illumination adjustemt, combined with the high degree of image enhancement. Some cloud motions are just perceptible, but very small from this distance, and within the short time. So, you may or may not notice them at a small number of locations during scene blendings.

Any residual issues in the movie are due to imperfect image processing. The movie may nevertheless provide you an idea of Juno's Perijove-09 flyby. The raw images used for this movie rendition are available via the missionjuno website.