Jupiter on the Shortest Day.

[Geoff Barnes]

It gets dark shortly after 5pm here now, and with a clear sky and temperature at 5 above freezing I ventured onto the front lawn with the 12 inch Dob for a look at Jupiter just clearing the 50 metre tree tops to our northeast.

After checking collimation by defocusing on Sirius (which showed a perfectly centred circle) I swung round 180 degrees and lined her up with my el-cheapo Saxon 7-21mm zoom.

Not too bad on wide angle but far too fuzzy on 7mm. Time to put in my surprisingly good generic 6mm 66 degree eyepiece.

WOW! There he was, so clear, so sharp! I could easily make out both north and south equatorial and tropical belts, and right in the middle of the sphere was the GRS.

Not only that, right on the outer limb was the sharp black shadow of one of the moons (don't know which one) just about to rotate out of view, super timing!

Cloud sheet moved in and spoiled the show, not that I minded as my hands and feet were getting slightly frozen, but I was more than thrilled with what I'd seen on only my second light with the new scope.

I can't wait to get a really high quality eyepiece around 5mm or so to blow my socks off!

[John]

Great report Geoff ?

Jupiter does not generally respond that well to really high magnifications here in the UK. I find 180x - 240x the max thats useful even with my 12" dob. Maybe thats different down under ?

Just got the shortest darkness hours here of course !

You should be able to make out Sirius B, the "Pup" star at around 250x with a decent low scatter eyepiece such as an orthoscopic.

I find Cartes Du Ciel good for finding out where the GRS is and which moon is which - it seems more accurate than Stellarium.

[Geoff Barnes]

 

1 hour ago, John said:

Jupiter does not generally respond that well to really high magnifications here in the UK. I find 180x - 240x the max thats useful even with my 12" dob. Maybe thats different down under ? 

I suspect with a combination of us being 500 metres above sea level and with frequent dry air funneling in from the parched Oz interior we probably get much better seeing conditions than many parts of the UK.

Once I get a short FL eyepiece and try it out I'll report back on my findings!

[barkis]

Ah! great stuff. Big Jove looks fantastic in a good telescope.
If seeing conditions are good, ie no turbulence in our atmosphere, 
no surrounding building shedding their daytime heat into the night sky,
then the detail can be astonishing. The Jovian moons too add to the splendour of
Jupiter, their slow dance around the planet can be observed if your observing period lasts long enough.
The shadow transits across the planets disc offer another spectacle to admire.
That huge, and seemingly perpetual storm that is the Great Red Spot is one of the giant planets enigmas.
Studies by probes, and earth bound equipment are revealing much more about  the planet too.
 

Of course, you have many treats in store for you, not least Saturn, the Jewel of the suns family,
there's a sight to blow your socks off, and much much more awaits, but take time to study 
these gems a while, it is easy to say Wow, and then move on. spend a little time really looking at 
these objects, they can sometimes reveal more when your eyes rest on them for periods of time, instead of a cursory
glance.
Enjoy your night sky adventures, and don't forget to get others involved, they will appreciate you introducing
them to the night sky too.
Best Wishes.

 

[Geoff Barnes]

Lovely words thanks barkis.

Im looking forward to many wonderful nights exploring and discovering ahead of me.

Particularly when the weather warms up again, I'm not a great fan of lingering out in the cold!

[Stu]

1 hour ago, John said:

Jupiter does not generally respond that well to really high magnifications here in the UK. I find 180x - 240x the max thats useful even with my 12" dob. Maybe thats different down under ?

I suspect that being at 67 degrees altitude allows a fair bit more mag to be used John.

[John]

27 minutes ago, Stu said:

I suspect that being at 67 degrees altitude allows a fair bit more mag to be used John.

I agree Stu. Even in past years when Jupiter has been high in the sky though, I've found that the nature of what we are trying to observe on the planet, ie: relatively low contrast variations, seem to get washed out if you crowd on too much magnification

I still find that I can't beat the views of Jupiter when there is quite a bit of light still in the sky - the colours and contrasts seem even stronger then

 

[Stu]

12 minutes ago, John said:

I agree Stu. Even in past years when Jupiter has been high in the sky though, I've found that the nature of what we are trying to observe on the planet, ie: relatively low contrast variations, seem to get washed out if you crowd on too much magnification

I still find that I can't beat the views of Jupiter when there is quite a bit of light still in the sky - the colours and contrasts seem even stronger then

 

Perhaps it's a combination of things then, altitude, seeing, transparency and drier air?

[barkis]

As we know, Jupiter's gaseous  atmosphere is never still, and even though
that constant movement is barely perceptible from way down here, It must
be a retardant to sharpness. However, that said, we can't help but 
admire the superb images that appear on SGL and of course other sites.
The observer on good nights can be be satisfied with the eyepiece views, but 
they play second fiddle to CCD produced images unfortunately.
I could get a slap around the ears for saying that .
 

[John]

5 hours ago, Stu said:

Perhaps it's a combination of things then, altitude, seeing, transparency and drier air?

A "wobbly stack" within the wobbly stack ?