Pushing the Limits

[Geoff Barnes]

I'm really enjoying my 12 inch Dob these last few evenings, getting some wonderful views of the main four planets while they are favorably positioned down here.

Had a quick look at Venus before it sank below the tree tops. It amazes me how bright it still is (-4.4 magnitude) even though it is now just a fairly thin crescent.

Jupiter was next, now following Venus getting lower in the evening sky. Just caught the GRS on the edge of the disk before it disappeared around the rim.

Next in line was Saturn, quite high still and looking really sharp tonight. I was using my new 6.5mm Morpheus for 230x magnification, and as seeing was pretty good I decided to pair it with my 2x Celestron Ultima Barlow for around 461x, just for a bit of fun to see what was possible pushing the scope to its max. Pretty impressed with how bright the image still was, but it was a fairly wobbly view to be honest. However, just occasionally the image would stabilise for a few seconds and I am certain I caught sight of the Encke Division, a very fine whisp of a darker line right near the outer edge of the rings was definitely there, amazing!

Finally, over to Mars, a bit better tonight I thought, the south polar cap was absolutely glistening white and the darker regions in the southern hemisphere were really quite a bit more obvious than previous views I've had.

Full(ish) moon coming up, a few clouds rolling in - time to pack up after another brilliant session! ?

[Rob]

Sounds great!.. I have to say a dob is on the 'get list' for me.. but its going to be next year!. nice report thanks

[John]

Nice report Geoff !!

Did you see Saturn's C or crepe ring ?

Not to be contradictory but I suspect what you saw was the Encke Minima which is a darkening of a portion of the A ring. The Encke Division itself is apparently difficult to see even with an 18" scope under perfect conditions. The Encke Division or Gap is 0.05 arc seconds in extent.

Sounds like you are having a better planetary season than we are here. I've had some "nice" views of Jupiter and Saturn this year but none as outstanding as I've had in other years, I suspect mostly because of the low altitude of the planets from the UK. Mars has had a large appaent diameter but so far the surface details have been highly muted so say the least !

 

[Geoff Barnes]

6 hours ago, John said:

 Did you see Saturn's C or crepe ring ?

 I suspect what you saw was the Encke Minima .

 

Hi John, yes you're quite right, the Encke Minima it must have been, but it was clearly there. No way could I see the Division with my scope!

The C Ring is a feature I can often see on a good steady night, not a distinct feature, more of a diffuse fringe on the inside edge of the B Ring.

[John]

2 minutes ago, Geoff Barnes said:

The C Ring is a feature I can often see on a good steady night, not a distinct feature, more of a diffuse fringe on the inside edge of the B Ring.

Thats how I see the C ring too. A very diffuse band or fringe extending towards the planets disk from the inside edge of the B ring. It seems to stop around 50% of the way across the gap between the B ring and the planetary limb. I saw it earlier this evening with my ED120 refractor. Good seeing tonight.

[Sunshine]

There's something so satisfying about pushing around a large-ish dob.

[MarsG76]

Nice report.... I'm jealous that you spotted the Encke division at 460X.... I couldn't see it at 479X in my 14"... your collimation must be impeccable.

 

[Geoff Barnes]

1 hour ago, MarsG76 said:

Nice report.... I'm jealous that you spotted the Encke division at 460X.... I couldn't see it at 479X in my 14"... your collimation must be impeccable.

 

Hi MarsG76, you couldn't see it and neither could I, according to our friend John I was seeing the Encke Minima not the division. The Encke Division requires quite a bit more magnification and/or aperture it seems. Pleased to spot the Minima nevertheless, quite a satisfying feat with a 12 inch Dob! ?

[MarsG76]

51 minutes ago, Geoff Barnes said:

Hi MarsG76, you couldn't see it and neither could I, according to our friend John I was seeing the Encke Minima not the division. The Encke Division requires quite a bit more magnification and/or aperture it seems. Pleased to spot the Minima nevertheless, quite a satisfying feat with a 12 inch Dob! ?

There is not too many things in an eyepiece that can potentially keep me at the eyepiece for over an hour than a nice clear Saturn on a still & clear night  when at high power.. Saturn definitely has it.. but still no Encke division.. I had it at 479X with the 14", looked sharp and 406X on the 8" also super sharp, but no uncle Encke....

I tried going higher, 550X and 660X and sure the disc was huge but was starting to soften up, so super high powers were of no more benefit.

 

[Paz]

Great report and goes to show big dobs can do planets as well as the faint stuff.