Jupiter and the Opposition of Saturn

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Saturn was at its opposition on 20 July 2020, less than a week after Jupiter. The opposition of an outer planet such as Saturn or Jupiter occurs when the Earth passes between it and the sun. The planet is then directly opposite the sun in our sky and positioned closest to the Earth. This obviously makes it an ideal time for observing, although unfortunately both planets are currently close to the horizon. You may have spotted them close together in the south recently — they are very bright and easy to spot.

These images of Saturn are centred around 22:22 UTC, just 22 minutes after opposition which occurred at 22:00 UTC. Five of its 53 named moons are visible including Titan (the largest) on the far right. The Cassini division and some colour bands in the atmosphere are clearly visible. Note that Saturn is presented here with south at the top.

Likewise, Jupiter is presented here with south at the top. Three of the four Galilean moons are visible (the other one, Callisto, did not fit on the camera sensor). Jupiter’s famous Great Red Spot (a gigantic storm) is also clearly visible, as well as its colourful clouds, arranged into bands of different latitudes.

Frames

• Saturn: 3× 3-min sequences of 20-ms light frames
• Jupiter: 3× 1-min sequences of 20-ms light frames
• 60× dark frames (no other calibration frames used)

Processing

• Each 3- or 1-min sequence (for Saturn and Jupiter respectively) was calibrated in PIPP. The 50% best frames were stacked in AutoStakkert! One output image was produced per sequence which was sharpened with wavelets in Registax.
• The resulting three images for each planet were then derotated and combined in WinJUPOS (to avoid smearing of details due to the rotating planet).
• Final processing was carried out in Photoshop.

Equipment

• Explore Scientific ED 102 mm Apo f/7 refractor
• Sky-Watcher EQ5 PRO SynScan GOTO equatorial mount
• Altair GPCAM3 290C colour camera (with UVIR window fitted)
• Celestron X-Cel LX 3× Barlow