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An evening with Jupiter, Ganymede and friends….


Stu
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Last night I had that rare coincidence of clear skies, no need to get up at 4am the following morning, permission from SWMBO to observe, and enough energy to actually do it! I noted that there was a transit of Ganymede occurring, so setup my kit relatively early on to catch it.

I was using my quite new APM LZOS 130mm f6 refractor on a Rowan AZ100 mount and Berlebach Planet tripod. This setup is quite chunky to put out, but obviously a delight to use. The mount has encoders fitted, and I tried these out for the first time last night using an AstroDevices Nexus connecting to my iPhone running Skysafari. It’s a great setup and I had a quick spin around a few objects just to test the accuracy, and it popped M13, M57 and NGC457 very nicely in the field of view even with just a fairly rough alignment.

This time I switched the scope to the other side (from left to right) which made life easier with the fine focuser on the outside. Reaching the slo motion controls was still fine. I also found a balance point which was fine with anything from a nag zoom to an Ethos, giving smooth slow motion control despite being a bit back heavy with the Ethos.

The nearly six day old Moon was looking beautiful, a lovely orange colour. It’s so nice to have a good Southern horizon and darker skies at my new house. I had a quick look at the Moon which was showing some good detail but was quite wobbly so I then turned my focus to initially Saturn, then Jupiter.

In terms of eyepieces, I started off using a Nagler 3 to 6 zoom, but then switched to a Vixen 3.4mm HR which was an improvement, but perhaps a little too much in terms of mag at x229. Then I remembered (🤪) my latest acquisition, the Tak TOE 4mm which proved perfect at x195. To my eye, although the Nag zooms are excellent, the HR and TOE both provided a little more saturation and fine detail. Subtle but definitely a real effect.

Saturn looked the best I’ve seen it for some time. A and B rings clear, with the Cassini division clear much of the time in the outer thirds of the rings. The shadow of the planet on the rings was very obvious now we are past opposition, and there was some surface banding visible, though I’ve seen this better on other occasions. Finally, the C ring was subtly visible both against the dark sky and also against the planet’s surface.

In terms of moons, Titan was obvious, with Rhea and Dione on the limit, helped by averted vision. The sky was a little hazy so I suspect that prevented me from seeing any of the fainter ones.

On to Jupiter. By the time I first observed it at around 8.30pm, Ganymede was about 1/3rd of the way across the disk, and appeared as a dark disk, slightly fuzzy at the edges ie not quite as dark or well defined as a shadow transit. I observed on and off through until just around 11pm when Ganymede left the disk and showed a small separation. The effect I find fascinating is that it appears dark and very obvious when against the brighter centre parts of Jupiter’s disk, but when it approached the limb, the limb darkening obviously closely matched the albedo of Ganymede and it became invisible to me. The seeing, having been excellent for most of the time, also dropped off a little, making it more difficult. Presumably if the seeing is good enough, at some point it would become visible as a bright disk against the darkened limb. The next time I saw it was as a bright pimple appearing on the limb as it egressed.

As said, earlier on the seeing was good to excellent, and some fine detail was visible in the bands. Hard to count how many (what counts as a band??) but there were around 11 different zones visible, perhaps more.

Some pictures attached showing the scope setup on a previous occasion when I was using binoviewers, plus some screen grabs from a video I took which, whilst nowhere near as good as the visual view, do at least show some surface detail and the dark spot which is Ganymede. Good to have captured surface detail and the two other moons as well.

During the evening I saw a quite bright meteor zipping through Cygnus, and also tried a few targets using a 21mm Ethos. M45 was great despite being poorly positioned. M27 looked excellent even at this lower power, set in context with its surroundings. Sweeping through Cygnus and also around the Double Cluster was wonderful. Finally, finally, using the 4mm again gave me a wonderful split of Pi Aquilae, the best I’ve had with two beautiful airy disks with clear separation. Similarly the Double Double was amazing; four bullseye diamond targets on black velvet! Lovely stuff!

Thank you if you made it this far! 👍😀

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Excellent report Stu :icon_biggrin:

I'm on holiday enjoying some good weather on the Isle of Wight but with no scope but it was nice to be reminded about whats going on up there !

I'll be looking forward to observing again when I get back home.

 

 

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Nice report. I agree seeing was very good last night with a lot of details on Jupiter. You seem to have very nice observing spot up on the hill.

56 minutes ago, Stu said:

I saw a quite bright meteor zipping through Cygnus

I may have spotted the same one, a very bright one around 11pm in Cygnus that lasted for a couple of secs. 

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3 minutes ago, Kon said:

Nice report. I agree seeing was very good last night with a lot of details on Jupiter. You seem to have very nice observing spot up on the hill.

I may have spotted the same one, a very bright one around 11pm in Cygnus that lasted for a couple of secs. 

Thanks. Yes, it was good for most of the evening then just dropped off towards the end. Actually that was much as predicted on the Jetstream forecast which showed it clear of the south west earlier but just dropping down over me a bit later.

My southern horizon is great now! Such a nice change not to have to spot the planets between the houses. I am observing over the town, but it’s only quite small and lighting seems well shielded. There is a rugby pitch to the south of us, but even when their floodlights are on it is still DSLR enough to observe, so they must be directed downwards and well shielded which is great.

Sounds like your meteor may have been different, and better than mine which zipped across in under a second. The other week I saw a beauty which lasted seven or so seconds, breaking up towards the end.

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14 minutes ago, Kon said:

Nice report. I agree seeing was very good last night with a lot of details on Jupiter. You seem to have very nice observing spot up on the hill.

I may have spotted the same one, a very bright one around 11pm in Cygnus that lasted for a couple of secs. 

Yes, I also saw a meteor at the same time and place. I’d put money on it being the same one!

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Great post. I caught the same transit last night too on my 8" SCT, my first ever and it was glorious. How did you know it was Ganymede? I fancy myself one who understands these things with literal 5,000+ hours into Kerbal Space Program but I can never discern what moon is what around Jupiter because of the obvious perspective problems

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2 minutes ago, HiveIndustries said:

Great post. I caught the same transit last night too on my 8" SCT, my first ever and it was glorious. How did you know it was Ganymede? I fancy myself one who understands these things with literal 5,000+ hours into Kerbal Space Program but I can never discern what moon is what around Jupiter because of the obvious perspective problems

The SkySafari app is a brilliant tool for information like this.

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1 minute ago, HiveIndustries said:

How did you know it was Ganymede?

By cheating 🤣.

SkySafari shows the position of the moons, including moon and shadow transits. Very handy. There are others such as Stellarium, JupiterMoons which work well too.

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Although saying that, I have found it is possible to identify Ganymede from its disc size compared to the other 3 satellites. Can’t tell the others apart though, probably why it is so easy to determine which one is Ganymede.

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Nice report Stu. I also used SkySafari to try and track down Ganymede last night but it was very difficult in poor seeing. After 30 minutes I was just picking it up, but don’t think I would have without SS.
Look forward to your views on the TOE 4mm - particularly in good seeing. With the 3.4HR, should make a perfect planetary pairing

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35 minutes ago, Highburymark said:

Nice report Stu. I also used SkySafari to try and track down Ganymede last night but it was very difficult in poor seeing. After 30 minutes I was just picking it up, but don’t think I would have without SS.
Look forward to your views on the TOE 4mm - particularly in good seeing. With the 3.4HR, should make a perfect planetary pairing

Shame the seeing wasn’t better Mark. It was pretty good down here so Ganymede was obvious most of the time. Interesting that the Jetstream forecast showed the South West being clear of it until 9pm ish, I noticed the seeing dropping off after about 10pm I think so it was fairly accurate. Possibly a fluke but perhaps not.

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I didn’t manage to get out on Monday night but it did look good outside. Great report.

Which diagonal did you use with the TOE and HR EP’s?

I’m seeing more with a more detail on planets with a mirror diagonal over a prism. I suspect the LZOS is well figured enough it does not need any correction that the prism is providing.

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57 minutes ago, Deadlake said:

I didn’t manage to get out on Monday night but it did look good outside. Great report.

Which diagonal did you use with the TOE and HR EP’s?

I’m seeing more with a more detail on planets with a mirror diagonal over a prism. I suspect the LZOS is well figured enough it does not need any correction that the prism is providing.

Thanks.

I used the BBHS mirror diagonal, didn’t try the prism last night. May try comparing them next time but just wanted to settle and enjoy the views on Monday. I think the marginal differences gained by switching kit constantly are normally offset by sticking with one setup and benefitting from the best moments of good seeing. It’s very easy to get tricked into thinking one thing is better than another, when actually it is just variability in seeing conditions.

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I did see a small but clear difference between the Nag zoom and the Vixen HR and TOE. They have slightly better detail and richer colour I thought.

Not possible to compare the HR and TOE really as the mag difference was too great. Even so, I would put them on a par with each other.

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It's great to observe through someone else's eyes once in a while, through great observing reports such as this one Stu.
You were lucky to get the combination come together and have a great night.
It was a lot more on/off here and the combination did not come together for me.

Nice to see that my (😉) 4mm TOE is working so well for you.....for those not knowing it was the one in stock at FLO and I was wavering the buy it button, when Stu went for it.

That kit you have now got is most desiarable indeed and will bring ongoing pleasure for some time.
Be careful though, a larger eyepiece case or another one now beckons

Interesting that you have now got the encoders up and running with a Nexus, they work well don't they.
I presently have the Nexus DSC on my Dob, love the easy finding, this will move over to the Rowan mount when it arrives.

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1 hour ago, Stu said:

It’s very easy to get tricked into thinking one thing is better than another, when actually it is just variability in seeing conditions.

I've repeated over numerous nights and at different times, but get the same result the mirror diagonal is better on Jupiter and Saturn on the LZOS, I suspect a different answer on my 100 mm doublet...

By better the Vixen HR will show belt detail on Jupiter with the mirror diagonal but not with the prism diagonal.

PS. I know some else who is waiting 60-90 days for the next TOE 4 mm to come into stock....

Edited by Deadlake
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22 minutes ago, Deadlake said:

I've repeated over numerous nights and at different times, but get the same result the mirror diagonal is better on Jupiter and Saturn on the LZOS, I suspect a different answer on my 100 mm doublet...

By better the Vixen HR will show belt detail on Jupiter with the mirror diagonal but not with the prism diagonal.

PS. I know some else who is waiting 60-90 days for the next TOE 4 mm to come into stock....

It definitely varies by scope; I had better results with a prism in the two Scopetech long focal length refractors, but am sure the correction and speed of the f6 means a mirror is the better choice.

I assume it’s the Zeiss prism you are using?

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1 hour ago, Alan White said:

It's great to observe through someone else's eyes once in a while, through great observing reports such as this one Stu.
You were lucky to get the combination come together and have a great night.
It was a lot more on/off here and the combination did not come together for me.

Nice to see that my (😉) 4mm TOE is working so well for you.....for those not knowing it was the one in stock at FLO and I was wavering the buy it button, when Stu went for it.

That kit you have now got is most desiarable indeed and will bring ongoing pleasure for some time.
Be careful though, a larger eyepiece case or another one now beckons

Interesting that you have now got the encoders up and running with a Nexus, they work well don't they.
I presently have the Nexus DSC on my Dob, love the easy finding, this will move over to the Rowan mount when it arrives.

Thanks Alan!

Yes, it’s great when everything comes together, and the seeing makes it all worthwhile. I’m hoping my new location will give me more consistent local seeing conditions but we will see. Always at the mercy of the Jetstream of course.

Always pleased to remove temptation from others! It’s nice when others do the same too, like @callisto grabbing the TS CC8 to stop me doing anything silly! I’m very pleased with the TOE 4mm, almost wish there was a 4.5 and a 5, might have to look at Delites, Delos or XWs…..

Very pleased with my setup now, I think I can settle on this and just enjoy it. I do need a pier extension for the Tripod to make life more comfortable. I have an 8” Skywatcher pillar which I can make work for the moment, but hopefully Rowan will produce something matching in the not too distant future. Picture attached of me mocking it up in my rather untidy garage!

I’ve got a very shabby case containing my 2” eyepieces currently which I need to sort out better, or use another spare case I’ve got. The 1.25” eyepieces have now migrated to their own case.

I was very pleased at how easy the Nexus was to get setup, without any instructions. The only thing I had to check was the number of clicks used by the encoders. 152,000 is pretty high! Explains the accuracy I guess. I think the DSC is great, but it’s also good that you can get the benefit of the encoders linking to SkySafari with the cheaper Nexus option in case you don’t need all the DSC functionality.

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