Dione Transits Saturn!

[Paul G. Abel]

Greetings everyone!

We had a clear sky for a time here in Leicester last night and I was able to observe both Dione and its shadow transiting Saturn's disk- t'was quite a sight!!!

I've never been able to observe a Satellite of Saturn crossing the disk, it's always been cloudy or not visible from UK etc! Anyway, here's a drawing of it. Seeing conditions were only average and there was some mist forming.

-Paul.

[mike bacanin]

Hi Paul,

As a fellow planetary observer who also likes to draw, i appreciate the excellent artistic rendering of your sketch.

However, you appear to show what appears to be the Encke minimae at the ring ansae.

I find it difficult to imagine such detail would be visible in average UK seeing.

On CN, the very experienced observer Sol Robbins does not show this level of detail in usually excellent seeing at such narrow ring tilt.

I'd appreciate your comments.

Mike

[Paul G. Abel]

Hi Paul,

As a fellow planetary observer who also likes to draw, i appreciate the excellent artistic rendering of your sketch.

However, you appear to show what appears to be the Encke minimae at the ring ansae.

I find it difficult to imagine such detail would be visible in average UK seeing.

Hi Mike.

It's not just seeing but the consistency of the atmosphere. In Leicester we tend to get this slightly pinkish high level mist, especially in spring and autumn and this has the effect of making the image of planets very steady indeed in the eyepiece.

Moreover, it's not about just drawing. I systematically look at every part of the disk and rings to draw up an entire picture. My observations are not meant to be artistic, rather more a technical drawing.

Anyhow, be that as it may, I'm not sure the feature in question is Encke's division. To my eyes there is a very real and definite darkening to the outer A-ring. This darkening is very often a brownish grey colour, and my observations over the last few Saturn apparitions show that there is some variation in intensity to the outer part of A-Ring. Whether it really is a genuine feature on the rings or some sort of contrast effect remains open to question.

The inner half of A-ring up to Cassini's Division is always much lighter and of a light grey colour. The effect is unmistakable (for me) and I have seen it with apertures ranging from 8 inches to 16 inches. If you look at David Gray's drawings (who observes from County Durham, UK) here

THE BRITISH ASTRONOMICAL ASSOCIATION

you will see he also records a similar shading to the outer A-Ring.

On CN, the very experienced observer Sol Robbins does not show this level of detail in usually excellent seeing at such narrow ring tilt.

I'd appreciate your comments.

Mike

I'm familiar with Sol Robins work, he is a very talented visual observer. I have to say that there have been occasions when he has drawn what looks like spokes and unusual features in the bright B-Ring with a 6 inch refractor (see J.L.Benton's book Saturn and how to Observe it, P93) and I have yet to see that with a similar sized refractor. I suppose in the end it may be that different people can pick up different contrast effects. Other than that I am at a loss to explain it.

[dweller25]

Paul,

The amount of detail you have put into your drawing is amazing.

Try as I do neither my 4" APO or 9.25" SCT show this amount of detail as sadly I live in the murk just north of Manchester.

I wish I had some of that pink mist.

[mike bacanin]

Hi Paul,

Thanks for your comments.

It may be worth noting that there is a difference between the Encke Division and the Encke minimae.

The division is an extremely narrow gap,similar in essence to the cassini division, whereas the minimae is more of a darkening in the A ring.

The Encke division was formerly known as Keeler's division.

The Encke minimae is much easier to observe than the extremely difficult gap.

Mike

[Paul G. Abel]

Paul,

The amount of detail you have put into your drawing is amazing.

Try as I do neither my 4" APO or 9.25" SCT show this amount of detail as sadly I live in the murk just north of Manchester.

I wish I had some of that pink mist.

Thanks dweller25. I have observed Saturn near Salford once and I have to say it was a real struggle to see the fine details! How do you go about getting a drawing?

For Saturn, I start off by looking at the extreme south pole and 'ask my eyes' what can be seen there, then gradually moving sowarthwards to EZ building up a complete picture of all the details that can be seen (it took me a while before I could see the really fine features) Then repeat the procedure for the northern hemisphere. For the rings I work outwards, start by looking at the A-Ring and work in until I reach the dark C-Ring, and so on.

Sadly that pink mist thickened into heavy cloud later in the night!

[Paul G. Abel]

Hi Paul,

The Encke division was formerly known as Keeler's division.

The Encke minimae is much easier to observe than the extremely difficult gap.

Mike

Well whatever it's currently called, for me there is a very real difference in intensity between the outer A-Ring and the inner A-Ring. I'm pretty sure Patrick Moore records a similar effect in his Saturn book I think with his former 8.5 inch reflector in Selsey. I'll check next time.

Paul.

[Talitha]

Paul, sincerest congratulations on witnessing the transit of Dione and its shadow!!! Your excellent rendering is probably the closest this Amateur will ever come to seeing it for herself... thank you.

Regarding the mist... I've found there's something about moisture particles in the air which seem to act as tiny lunar and planetary 'intensifiers' (for lack of a better word). The very best view I've ever had of Mars was through fog so thick the planet could not be seen naked eye.

[Paul G. Abel]

Paul, sincerest congratulations on witnessing the transit of Dione and its shadow!!! Your excellent rendering is probably the closest this Amateur will ever come to seeing it for herself... thank you.

Hi Talitha, thanks very much! It really was quite a sight and to be honest, I wasn't expecting to be able to see it!

Regarding the mist... I've found there's something about moisture particles in the air which seem to act as tiny lunar and planetary 'intensifiers' (for lack of a better word). The very best view I've ever had of Mars was through fog so thick the planet could not be seen naked eye.

Your absolutely right!!! You know one of my best views of Mars was also in the fog; thick sea fog in Selsey tp be precise. It seems counter intetuitive because the planets themselves look so dim and unpromising in the murk and yet the view on the eyepiece is simply stunning! I guess there's more to this visual observing lark than just the seeing!

PS You got a drawing of that Mars observation?

[Talitha]

Sorry Paul, there's no sketch. To be honest I don't even remember what year the observation was made, or if I was already sketching or not.

Touching on the fog again..

In the winter when it's cold enough to form breath-vapor in the air, try puffing a cloud of it towards the Moon and looking through it naked-eye. I'm not sure if the tiny droplets do anything more than help control the glare for a second, but Luna always looks sharper to me.

[ashenlight]

That is a beautiful sketch, Paul - congratulations. Such precise detail in there, it fills with me with as much awe as seeing Saturn through my eyepiece!

Keep up the good work, would love to see some more of your sketches.

Wishing you clear skies, with a bit of pink mist!

Amanda

[Andrew*]

I still struggle to understand how you get so much detail.

Looking at Saturn last week for ages at different magnifications, I could never discern more than a band on each hemisphere, and the gap between teh rings and the planet, and even those were a challenge:icon_scratch:

Quite extraordinary:icon_salut:

Andrew

[Paul G. Abel]

I still struggle to understand how you get so much detail.

Looking at Saturn last week for ages at different magnifications, I could never discern more than a band on each hemisphere, and the gap between teh rings and the planet, and even those were a challenge:icon_scratch:

Quite extraordinary:icon_salut:

Andrew

Well it isn't a skill I just suddenly developed! It's taken many years of practice at the eyepieces of various telescopes and experimenting with different types of eyepieces in different conditions. I should perhaps say that the image above is not what I see straight away when I focus Saturn in the eyepiece. It's the total picture I've built up whilest examining each section in turn starting with the SPR and moving down into the STZ, StropZ and so on.

I find with my 8 inch Skywatcher reflector, a WA Plossl eyepiece which gives a mag'n of 312x and this is very good for Saturn and Mars and the moon. For Venus I use a different eyepiece combined with a barlow lense which gives a power of 133x and so on.

[David Galvin]

Paul, when we last met, I meant to ask if you ever use filters in the eyepiece to enhance detail. I have often used them on the planets and found that they do help me to see some details such as blue wisps in the Jovian clouds or the polar ice caps of Mars.

P.S I enjoyed the Sky at Night yesterday evening, did you?

[Paul G. Abel]

Paul, when we last met, I meant to ask if you ever use filters in the eyepiece to enhance detail. I have often used them on the planets and found that they do help me to see some details such as blue wisps in the Jovian clouds or the polar ice caps of Mars.

Hi Dave! I'm just putting the finishing touches to my article on visual observing for your society. I don't use filters that often myself, but you are absolutely right they can really enhance the finer features. I have found blues do bring out the subtle shadings on Venus in particular. With Mars, Jupiter and Saturn however I have found that I can manage without them.

P.S I enjoyed the Sky at Night yesterday evening, did you?

I really did! You were fantastic Dave, such I pro. I guess I wasn't too bad (perhaps a little animated!) and I like the fact that they showed my Saturn book. Yey!!!!! We've done the Sky at Night!!!!!!

[Beyond_Vision]

Great sketch Paul, I was just watching the latest episode of the Sky At Night and spotted you on there. It's a real shame you didn't get to see the 4 moons transiting Saturn. I think I spotted you too David ?

Regards

Kevin

[David Galvin]

Yes Paul, the sketches came over really good on the screen but it was a shame that Pete and yourself were not shown discussing 'art or science'. Maybe it will be used in a later edition. I suspect that you will be on again mate, a rising star in the making. In the mean time I will be in the background staring at my laptop.

sorry for drifting off topic and shall now nudge us back on topic.

[Trevor]

Paul

If you can remember which book I will have a check next time I am there.

Well Mike it reads as if your are questioning Paul’s work?

I have watched Paul doing his work, in fact a friend and myself were imaging Saturn while Paul was sketching at the same time, something that does not happen very often, although the conditions at the time were less than favourable.

Paul’s work is outstanding and having seen him working I can fully appreciate the amount of work that goes into producing the finished sketch.

Trev.

[moocher]

I`ve done a bit of planetary drawing way back before i discovered the ToUcam pro but nothing i`ve drawn comes close to this!!!! What scope btw?

Alan:)

[Paul G. Abel]

Thanks for the support Trev- that was a good night at Patrick's wasn't it? I've never seen Mars so clearly- forgot how we compared drawings and images afterwards!!!

Hi Moocher, the above drawing was made with my 8 inch Skywatcher reflector, one of the best telescopes I've ever had! I recently bought a new WA Planetary Plossl eyepiece which gives me a magnification of 312x. Saturn is stunning at that magnification!

[Trevor]

No problem Paul I know your work well.

[Ant]

I have no idea if Paul is able to see what he draws or not and frankly for the purpose of this post it doesn't matter.

What really worries me is that you imply that we are not allowed to question Paul's work? I really hope that that isn't the case?

Well Mike it reads as if your are questioning Paul’s work?

[Starman]

A lovely sketch Paul.

Having seen Paul's observational records and drawing skills, I would have no doubt whatsoever that he records whatever he sees without prejudice.

[Paul G. Abel]

Many thanks Pete, many thanks indeed.

[mike bacanin]

Quote: [Well Mike it reads as if your are questioning Paul’s work?]

Yes, Trevor, you read correctly.

However this is a forum of free speech, and i'll say what i feel, as long as it is within the bounds of the COC

My comments are not an attack on Paul as a person, they are directed at the details rendered on his sketches of saturn.

Whilst i do not doubt a fair part of what is depicted is there, i believe artistic license has crept in to a degree.

I feel the mottling detail in the bands is dubious, as are the renderings of encke minima in the rings, which seem to appear in most of the saturn sketches.

why do i feel this way?

1) the instrument used, whilst an ok scope, is not exactly optimized for high resolution planetary detail, and nowhere in comparision to really high quality instruments dedicated to planetary work of that aperture.

2) The eyepiece is not one that is of the highest quality for resolution of difficult low contrast details.

3) the typical seeing conditions are well under optimum needed to see this level of detail. If we were talking Chile i could accept it.

Paul even states the seeing is average.

Sorry Paul and friends, its not sour grapes, rather a constructive criticism from a keen planetary and lunar visual observer .

check out the attached HST image taken in February.

even in the prefection of outer space you will not see the degree of the detail rendered.

This is my final post on this subject,and I hope that since i've been now open about my thoughts there will not be any misunderstandings.

Mike