Detail on Ganymede AND Callisto!

[iceman (Mike)]

Hi all

While capturing Jupiter on the 24th Feb (local time), I noticed a neat pairing of the satellites, with Ganymede and Callisto close together (a long way from the planet) and Europa and Io similarly close together but closer to Jupiter.

The 2nd attachment is a screenshot from "Jupiter 2" simulator, showing the position of the moons.

The 1st attachment is my capture of Ganymede and Callisto, which easily fit in the 640x480 FOV. The seeing was not much above average, but detail can still be seen on both moons. I'd love to try this again in better seeing.

Thanks for looking.

[ving (David)]

nice mike
I have seen better moon detail from you but the fact you got both of these adds extra kudos to the shot
thnx

[ballaratdragons (Ken)]

Not many people image the Galileans. Well done Mike. Be good to see images of them at higher mag in excellent seeing conditions.

[fringe_dweller]

nice job as usual!

[Dennis]

Sorry Mike, just not good enough. We want Io and Europa too....and a few geysers and sulphur plumes to boot!

Seriously thought, those are fantastic results, especially for so early in the season. Look forward to seeing more as Jupiter closes in.

Cheers

Dennis

[sheeny (Al)]

Well done Mike!

Al.

[Lester]

Good results Mike.

Can you answer this for me, when is detail, artifacts, or artifacts detail? I can remember about 2 months ago on Cloudy Nights someone got different colour shadings on Uranus and some were convinced it was artifacts.

I am not saying yours are artifacts by the way, and well done.

[Rodstar (Rod)]

That extra 2 inches of aperture is certainly bringing with it some extra detail Mike, great stuff.

[RB (Andrew)]

Reminds me of my early attempts at Mars..........

Seriously though, that's awesome Mike, like Rod said the extra 2" makes a big difference.

[GTB_an_Owl (Geoff)]

I think i can answer your question Lester

Re "shading on Uranus"

its a "detail" when its only a skidmark
when its more than a skidmark it could be classed as an "artifact"


hope the mod squad see's the funny side in that
sorry, i just couldn't let it pass as it were

[Ric]

Thats simply amazing Mike, my hats off to you.

Stunning work

[iceman (Mike)]

Thanks for the feedback guys.

Originally Posted by Lester

Can you answer this for me, when is detail, artifacts, or artifacts detail? I can remember about 2 months ago on Cloudy Nights someone got different colour shadings on Uranus and some were convinced it was artifacts.

I am not saying yours are artifacts by the way, and well done.

It's a good point Lester, no offence taken. We have to be very careful in our processing of planetary images because it's very easy to over-sharpen and introduce artifacts which can look like real detail.

For my images and processing, I know I've captured real detail when:
- I can see it in the raw files
- I can see it in the stacked data (before sharpening).
- I can also tell when it's real detail if I've captured it before and the same features appear in subsequent images - either taken on the same night or different nights.

I've taken at least 6-10 images both this year and last year that show detail on ganymede with similar markings, and compared to images from other planetary imagers who have captured detail on Ganymede, again it shows the same markings. So in that case I hope what I'm capturing is real.

I've never captured detail on Callisto before, and have only seen very few images where people have. So with this it's a little more difficult, as the target is also smaller and dimmer so it's very easy to introduce artifacts when trying to make it brighter and sharper.

For these images I did very little processing on them after stacking, with only mild wavelets in Registax, and mild LR deconvolution in AI before recombining into a colour image. In photoshop I used curves and levels and a bit of saturation to highlight what I considered detail by adding contrast.

I'll need to capture Callisto again in better seeing to confirm the colours and/or markings, i'm sure there are some colour artifacts on Callisto right now but i'm happy I've captured it as a disc at this stage.

I'm prepared to be wrong though, especially with dark markings in the center of a small disc which can easily appear even with light processing. I'll continue to capture the satellites this season when the seeing is good and hopefully be able to confirm one way or the other.

Thanks

[Lester]

Thanks for the explanaition, Mike.

[ballaratdragons (Ken)]

I have put together an image of the real Ganymede and Callisto in about the same orientation as you captured them, Mike, with yours in there too.

It does appear that you have captured similar surface detail on Ganymede.

I'm not sure that Callisto would give up any of her surface features though. She's a bit bland.

Well done.

[iceman (Mike)]

Thanks Ken, and you're right. I've had some discussions with John Rogers and Giovanni Adamoli, who use my images in the ALPO program, and they've confirmed there's definitely albedo features in the ganymede I've captured (and that they match with solar system simulators), however with Callisto there aren't any significant craters or rays that would be easily captured as albedo markings.

So with Callisto, it looks like the most I'll be able to capture this year is a nice round disc with accurate colouration, rather than albedo features. I'll keep trying!

[gaa_ian (Ian)]

Good on you Mike, its always good to push the envelope !
I hope i can get that detail visually with the 18" when the weather improves