Second try at planetary - Jupiter

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timh
Posts: 573
Joined: Mon Aug 26, 2019 5:50 pm

Second try at planetary - Jupiter

#1

Post by timh »

Thanks to the advice on the forum, Sharpcap's live stacking, time travel autostack option, ability to continuously monitor stack quality and therefore identify short windows of better conditions - I was finally able to get some much better-detailed images than before.

Equipment was again a VX12 300 mm Newtonian F 4 on a CEM70 mount with a ZWO ASI 715 MC camera (which has tiny 1.45 uM pixels) and Baader UV/IR cut off filter but this time the light train included a 2X Barlow (probably working at about 1.8X). The image scale was therefore ~ 0.125 arcsec/ pixel giving a sampling rate of ~ 3X versus the Dawes limit of ~ 0.4 arcsec.

The ROI was set to 800 x 600 pixels at gain ~ 145 using fast mode at RAW 8 with the ADC set at 10 bit depth to maximise FPS. The planet was tracked with the Camera ROI.

Jupiter was variously imaged using a combination of normally-collected .ser files, time travel .ser files and TIFF file snapshots of the ongoing ~ 1000 frame stack (at a capture rate ~ 25-40 fps, 12- 20 ms, stacking the best 50% of each 300) and continuously monitoring the quality of the stack. Each .ser file capture was about 38-43s long and each was post processed in Sharpcap into a single auto-adjusted and sharpened .tiff. Finally the sets of .tiff snapshots so-obtained were combined together in sets of 4 or 5 within a 3-4 min window using Winjupos and - optionally -slightly resharpened using Registax (I am not sure that this made it any better -- the pre-Sharpcap sharpening was enough probably).

The quality monitoring facility of Sharpcap is really useful since it puts hard numbers on what would otherwise be merely an impression of quality as to the best time to capture. The quality scale seemed to work that a score of about 2.3 means really too fuzzy to bother to capture whereas - at its best - a score of about 4.4 corresponds to really quite an impressively sharp image. There was a short (~ 3 minute) window on 02/02/25 with scores above 4.3 and the best image was compiled from frames taken over that period (just after the GRS had disappeared to the west and Io had just ducked behind the western limb).

The images show the winjupos image compiled from 6 such snapshots, as it came and also further slightly sharpened in Registax - not sure which is best - I think unsharpened - and also - at the top - a single live stack snapshot (800 frames) at a quality score of 4.4 which illustrates the EEA aspect of using SC livestack. South is up and East is to the left of the images.

Tim
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Snapshot at 21_26_34 of Stack_00002_best.jpg
Snapshot at 21_26_34 of Stack_00002_best.jpg (60.32 KiB) Viewed 608 times
2025-01-30-2126_5-tim_top6at2125_registax_affinity.jpg
2025-01-30-2126_5-tim_top6at2125_registax_affinity.jpg (156.01 KiB) Viewed 608 times
2025-01-30-2126_5-tim_affinity_unsharpened.jpg
2025-01-30-2126_5-tim_affinity_unsharpened.jpg (118.98 KiB) Viewed 608 times
Last edited by timh on Tue Feb 04, 2025 10:14 am, edited 2 times in total.
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turfpit
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Re: Second try at planetary - Jupiter

#2

Post by turfpit »

Tim

Very good. Middle image for me - more detail on the bands.

Dave
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admin
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Re: Second try at planetary - Jupiter

#3

Post by admin »

Hi Tim,

lovely images and a nice writeup - I agree with Dave that the middle one is the stand-out image of the set with a really good amount of detail in it :)

One thing I will note for the benefit of anyone reading this thread who is about to try planetary stacking - the quality numbers that Tim mentions need to be treated as relative numbers and specific to a particular combination of telescope/camera/target/camera settings/etc. In Tim's setup 2.3 is very poor and 4.4 or so indicated good quality. With my setup a couple of nights ago, 9 to 10 was poor and 12 or more was good. So, don't worry about the quoted values for good/bad/indifferent quality - watch the values that your setup produces and how they vary over time.

cheers,

Robin
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