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First Jupiter Shadow Transit & Saturn Cassini Division


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Posted (edited)

After a mixed but fun night of south easterly cluster sweeping & wrestling with neighbourhood security lights I got an amazing hour of planetary viewing. 
 

I had the ST80 in wide field mode and Hilkin 60mm f13.3 out earlier, but the crisp view of Saturn in the Hilkin sent me scuttling inside at 2am to fetch the 127 Mak - so glad I did.  
 

Amid sonetimes bobbly seeing I got occasional periods of really stable viewing allowing me to see the Cassini division for the first time, at times on both sides of the disc but more reliably to the W. 
I could also sonetimes see a band in the Northern hemisphere. Both features were much easier to spot when I remembered to switch the Neodymium filter over. 
Best view was at 150x with a 10mm Baader Classic Ortho. Views improved markedly after about 20 minutes as the hurriedly deployed Mak cooled from its semi-outdoor store to a chilly pre dawn level. 
 

Stepping back for a rest, Jupiter was really blazing away by now so I reluctantly tore myself away from Saturn and had an amazing view.  Multiple bands & something on the Western limb that I at first thought might be the GRS but with careful focussing and prolonged viewing I became convinced was a shadow transit. I watched until local ground mist started to impede seeing, & by this time contrast was fading a bit with the lightening sky (amazing as only just gone three!). 
 

Coming inside and checking online I realise there was a special merged shadow transit tonight - I only caught it after the shadows were one but feel incredibly exhilarated nevertheless. 

A session I will never forget! 
 

Edited by SuburbanMak
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Great report.... I agree that Jupiter and Saturn are fantastic views during clarity.... along with Mars during clear opposition time...

I remember when I could view Jupiter  and Saturn at 406X during a clearest night and the view was staggering.. I couldn't take my eye off the eyepiece.... the planets were massive and the amount of detail in the planets was photographic.  This was through my C8... once through the 14" dob I had a view of Jupiter at 480X with the GRS that was sharp as a tack... the GRS was surrounded with fine detailed cloudband and had a darker speck visible within.. the moons were like little discs not just points.. awesome planets to view.

I'm hanging for such views again...

 

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8 hours ago, SuburbanMak said:

Coming inside and checking online I realise there was a special merged shadow transit tonight - I only caught it after the shadows were one but feel incredibly exhilarated nevertheless. 

Great report. That sounds really cool, I’ve seen multiple shadow transits before but not merged like that. I checked it out in SkySafari, snapshots here of merged at 1.33 am then unmerged. Nice catch 👍

These two are fabulous when the seeing is good.

6FB5ECF4-E8F3-4722-8AFF-E624F064D294.png

9A844A20-039B-4ABA-952A-FB6C087EC245.png

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Posted (edited)
3 hours ago, Stu said:

Great report. That sounds really cool, I’ve seen multiple shadow transits before but not merged like that. I checked it out in SkySafari, snapshots here of merged at 1.33 am then I merged. Nice catch 👍

These two are fabulous when the seeing is good.

6FB5ECF4-E8F3-4722-8AFF-E624F064D294.png

9A844A20-039B-4ABA-952A-FB6C087EC245.png

Thanks Stu - it looked more like your first screenshot by the time I saw it and was further West. (L in Mak) Trying not to kick myself for missing the merge as it was so amazing anyway & I had no idea it was happening. 
 

I will definitely be in the lookout for visible transits future, quite a mad thing so see when you imagine it’s a total solar eclipse happening half a billion miles away! 
 

 

Edited by SuburbanMak
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2 hours ago, SuburbanMak said:

quite a mad thing so see when you imagine it’s a total solar eclipse happening half a billion miles away! 

Very true, hadn’t thought of it quite like that before! The shadows are amazing, jet black and sharply defined. It’s interesting to watch at opposition when the Moons can overlap the shadows because everything is lined up, Sun, Earth, Galilean Moon and Jupiter.

88F37C40-659D-45AE-B55F-99BC2A8B9680.png

499D2A81-D512-4EFF-88DF-43C4BE93DA5E.png

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5 hours ago, Stu said:

Very true, hadn’t thought of it quite like that before! The shadows are amazing, jet black and sharply defined. It’s interesting to watch at opposition when the Moons can overlap the shadows because everything is lined up, Sun, Earth, Galilean Moon and Jupiter.

88F37C40-659D-45AE-B55F-99BC2A8B9680.png

499D2A81-D512-4EFF-88DF-43C4BE93DA5E.png

That looks amazing - I will keep an eye on the transit timetable, well worth staying up for (always going to work so much better for me than getting up at 2 am, once I’m out that’s it!). 

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11 hours ago, MarsG76 said:

Great report.... I agree that Jupiter and Saturn are fantastic views during clarity.... along with Mars during clear opposition time...

I remember when I could view Jupiter  and Saturn at 406X during a clearest night and the view was staggering.. I couldn't take my eye off the eyepiece.... the planets were massive and the amount of detail in the planets was photographic.  This was through my C8... once through the 14" dob I had a view of Jupiter at 480X with the GRS that was sharp as a tack... the GRS was surrounded with fine detailed cloudband and had a darker speck visible within.. the moons were like little discs not just points.. awesome planets to view.

I'm hanging for such views again...

 

Wow - those are some high magnifications. I did crank it up to around 300x last night for a while but got much more detail un-Barlowed at lower Mag.

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There will be another moon shadow transit on Jupiter tomorrow morning starting at about 4am: the shadow of Europa will be visible and the great red spot. 

4am is already quite light, but say about 150x the sky background is dark enough for good contrast and Jupiter is high enough to good seeing. 

I am planning to get up for this, an hour of observing and then can start the day early :)

 

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Hi SuburbanMak

Just wanted to venture a thought about your views of Saturn. I too have seen a surface band on Saturns surface but I am undecided if it is actual weather on the gas giant or a shadow from the planets ring formation.

I am not sure how to find out but I am sure there must be resources that would show such info, please feel free to chip in #Stu as I know you are more than familiar with planetary observing, to say the least.

Good work SuburbanMak, nothing like fantastic views of the satellites with special features👍 
 

Marvin

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21 minutes ago, Marvin Jenkins said:

Hi SuburbanMak

Just wanted to venture a thought about your views of Saturn. I too have seen a surface band on Saturns surface but I am undecided if it is actual weather on the gas giant or a shadow from the planets ring formation.

I am not sure how to find out but I am sure there must be resources that would show such info, please feel free to chip in #Stu as I know you are more than familiar with planetary observing, to say the least.

Good work SuburbanMak, nothing like fantastic views of the satellites with special features👍 
 

Marvin

You can indeed see weather bands on Saturn’s surface. They are a lot more subtle than Jupiter but certainly visible.

You can see the gap between the rings and the planet, obviously, but also the shadow of the planet on the rings behind. This depends on where the planet is in relation to opposition. At opposition the shadow falls directly behind the planet so is not visible.

In the rings you can see the A, B and C (or crepe) ring, and the Cassini division between A and B. This image shows some of the visible features. I think I may have seen the Enke gap many years ago when Saturn was much higher in the sky, but I was very inexperienced then so may have been mistaken. Will have to wait until 2032 when it is back at its highest and hope my eyes haven’t given out completely by then!

F19A5396-E881-4AA3-935E-00816B222B70.jpeg

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18 hours ago, Nik271 said:

There will be another moon shadow transit on Jupiter tomorrow morning starting at about 4am: the shadow of Europa will be visible and the great red spot. 

4am is already quite light, but say about 150x the sky background is dark enough for good contrast and Jupiter is high enough to good seeing. 

I am planning to get up for this, an hour of observing and then can start the day early :)

 


Hope you got to see it Nik - I baled out at about 1.30 as a school night! 
 

What software are you using to predict? Am yet to see the GRS & would love to be able to work out timings. 

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Posted (edited)
15 hours ago, Marvin Jenkins said:

Hi SuburbanMak

Just wanted to venture a thought about your views of Saturn. I too have seen a surface band on Saturns surface but I am undecided if it is actual weather on the gas giant or a shadow from the planets ring formation.

I am not sure how to find out but I am sure there must be resources that would show such info, please feel free to chip in #Stu as I know you are more than familiar with planetary observing, to say the least.

Good work SuburbanMak, nothing like fantastic views of the satellites with special features👍 
 

Marvin

Hi Marvin - I am fairly certain it was a cloud band rather than shadow, looked like a lower contrast version of the bands on Jupiter. Was quite faint and present only for a few seconds at a time but did see it multiple times over about an hour. 
 

From @Stu’s diagrams above (thank you for those excellent stuff!) I would say I was looking at the North equatorial belt. 

I could see the Cassini division but not distinguish between the B&C rings. Again this came and went with the seeing. 
 

Also Titan and one other moon very evident (there are a few around 10th magnitude, not sure which I was looking at that night). 

Edited by SuburbanMak
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2 hours ago, SuburbanMak said:


Hope you got to see it Nik - I baled out at about 1.30 as a school night! 
 

What software are you using to predict? Am yet to see the GRS & would love to be able to work out timings. 

I have found that the desktop version of Stellarium is quite accurate for both transits and GRS, while the mobile version gives moon transits accurately but its predictions for the GRS are off by more than an hour. As a quick reference Project Pluto is very good: https://www.projectpluto.com/jeve_grs.htm

Today I overslept and only got at the scope at 4:45am by which time Jupiter was no longer prominent with naked eye. It took me some time to spot it in the finder, but eventually I managed  it (I'm using EQ5 in manual mode, very quick to start observing but hard to find objects you can't locate approximately at least with naked eye.)

In the telescope at x180 the view of Jupiter was very sharp and the shadow of Europa was easily visible between the two main bands. The GRS had rotated out of view.

The contrast was not the best, because of the daylight, but the seeing was excellent. I could  see multiple bands and even a hint of festoons near the equatorial belts. I just wish I started 40mins earlier, looked like a great conditions for high magnification planetary observing. 

As Jupiter rises earlier every day, in a few weeks we can see it higher in altitude  in the darkness for best views.

Clear skies!

 

Nik

 

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10 minutes ago, Nik271 said:

I have found that the desktop version of Stellarium is quite accurate for both transits and GRS, while the mobile version gives moon transits accurately but its predictions for the GRS are off by more than an hour.

Likewise SkySafari has been about half an hour out for a while. Apparently there is an imminent fix due, but haven’t checked it yet.

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Being a cloud feature the GRS is not 100% predictable, it has been known to do strange things, even (slowly) fade, change colour and size, so  any software needs updating with an actual observation on a regular basis. Project Pluto page says it's updated at the beginning of each year.

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59 minutes ago, Nik271 said:

Being a cloud feature the GRS is not 100% predictable, it has been known to do strange things, even (slowly) fade, change colour and size, so  any software needs updating with an actual observation on a regular basis. Project Pluto page says it's updated at the beginning of each year.

Yes, it does drift so the position needs updating fairly regularly, that’s the problem. That and making sure the light travel time from Jupiter is factored in, otherwise it appears about 35 to 40 mins before it actually does.

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