Saturn is one of those magical objects for visual observing. Surrounded by a disc (or rather multiple discs) of debris, Saturn is always great fun to look at and nice to photograph. The adjacent image was my first attempt, taken on 21 July 2018 23:00 UTC with the C11 using a 2 x Barlow and ZWO ASI174 camera. Seeing was far from great (a warm summer night), while the altitude was just under 14 degrees, resulting in this rather blurry image.
On 25 June 2019 seeing was quite reasonable. After having collected the data for the animation of Jupiter I had some disc space left for a bit of data of Saturn. It can be noticed that the disc is getting flatter again, now no longer visible behind the top edge of the planet. Imaging was done using a C11 EdgeHD with 2x PowerMate Barlow, ZWO ASI290MC and ZWO ADC. A total of 10000 frames was shot at 12ms shutter speed, 1000 of which were stacked to create this image.
On 29 June 2019 the forecast was good again, so another attempt was made on Saturn. Imaging was done using a C11 EdgeHD without Barlow, ZWO ASI290MC and ZWO ADC. A total of 60000 frames was shot at 5ms shutter speed, 12000 of which were stacked to create this image.
On 22 July 2019 seeing was very reasonable and so another attempt was made to get a proper picture of Saturn. This time I used both the C11 EdgeHD and the Esprit 150ED (2x PowerMate ZWO ASI290MC), but as the latter gave a slightly more detailed image, it is this one that is shown here. For the image 8751 frames were captured in 120 seconds, 20% of which were stacked in AutoStakkert with 3x drizzle and post-processed in PSP.
The Cassini divide is clearly visible, but with some imagination the Encke divide is visible as well. From outside inwards the visible rings shown here are divided in the following parts (there are other divisions at the outside).
If I checked out well in Stellarium, Saturn and Jupiter can be captured on one plate for three days this year (20, 21, and 22 December 2020) with the combination of C11 with ZWO ASI174MM (the image was captured without Barlow, but with ADC). Tonight (20 December) was the first chance, the two others opportunities will follow for the next two days. The circumstances were far from ideal: a lot of clouds, but fortunately also a few holes, and the planets at low altitude. Saturn was at an altitude of 11░ 13′, Jupiter at 11░ 04′. Their separation was roughly 9.5'.
Instead of using my usual 4 x 120s script, I set FireCapture up to make 30 second SER movies on demand. Then in between clouds (between 4:05 PM to 4:15 PM UTC) various recordings were made in LRGB, constantly manually adjusting the exposure to adjust for the thin cloud cover. In this way, several videos were recorded per filter, the majority of which had to be stopped well before the 30-seconds limit. The remaining movies, usually with no more than a few thousand frames, were subsequently stacked and the best chosen for further processing.
In the end the RGB stacks were combined into a colour plate and the L-stack used as luminance. Finally in PSP the colours were corrected and the brightness increased. The whole image was constantly processed as a whole to maintain the difference in brightness between Saturn and Jupiter. Jupiter also shows the moons Ganymede (left) and Europe. Io was in front of Jupiter at the time of the image, its shadow is just visible.
Click here for the full image.
If you have any questions and/or remarks please let me know.
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