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My Astronomy Class - Observing Saturn!


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Hi Folks,

As you no doubt have heard browsing these forums, Saturn is back this spring and it is magnificent! Many of us are getting ready to see Saturn for the first time, others are continuing a life-long love affair with the ringed giant. :)

My Saturn Observer's Log Sheet is attached, and consists of three parts - very useful for organizing and noting your results.

Part 1: Naked Eye sketch! Draw Saturn in the sky as you see it. Include constellations and major stars - use Stellarium after the fact to help you name things properly. Remember, every observation is a chance to learn your way around the sky!

Part 2: Moon Hunter! Starting at low power (60-80x), sweep the sky in the direction of the ring plane. The diagram on the observer's log will help you accurately place moons in relation to Saturn. The page is already divided into 'ring diameters'. Use Saturn itself as a measuring stick to locate and position moons properly on your diagram. You may wish to try the scan again at a higher power - say 150x. Averted vision (looking 'out of the corner of your eye') and the motion of objects across the field can help you detect fainter objects than you can reliably see with direct vision. Scan slowly and allow your eye to roam!

Part 3: Best Magnification! The best view may occur at different magnifications as you move through the night and Saturn climbs higher in the sky. Often the best view isn't the absolute maximum magnification, and the actual quality of the view will depend a lot upon seeing and transparancy - much more so than upon light pollution. Saturn is a fine target - even if you live in the city!

Use the Box Method to draw the rings accurately. Note outermost point, or 'elbow' of the rings on each side as well as the innermost point of the rings on each side, then note how far above and below the center of the planet the rings extend. Within this 'box' the rings will be a perfect ellipse. You will be surprised at how easily you create an accurate and beautiful drawing of Saturn.

Next, add ring detail. Shading to show brightness, dark lines for the gaps (if you can detect them!) should be added now. Next add any banding, polar or limb darkening you see on the planet. Last, add any shadows you see of the rings on the planet, or vice versa. Remember to comb the areas near the rings (just beyond the Roche Limit!) for small, faint moons. Any object you see here is most likely a moon, not a faint star. Try moving the disk of the planet just out of the field to make faint moons more visible against the dark background!

Good luck - and don't forget to scan and post your results!

Dan

Saturn Observer's Log.doc

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I have read a lot about people doing sketches of there viewings, but i absolutely hopeless at drawing anything (apart from stick men) so any tips are welcome, or should i just leave the sketches and make more detailed notes?

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Hi Gaz!

Take a look at the log sheet - there isn't much there to be afraid of, and a lot of it is pre-drawn for you.

As for the constellations - give it a try... it's only a few dots here and there, that can't be any harder than drawing a stickman, can it??? :)

This is all for fun and enjoyment anyway - don't worry about it if your sketch isn't up to British Museum standards! My sketches certainly are never anything much... that's why I keep the assignment so simple!

Dan

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Very good exercise, Dan. I've done a similar exercise without the sketching, just a word picture, when I've had less than 10 students with the scope. I take them each through the low power sweep, have them write a few sentences, then turn it in. Perhaps an hour later, we do it again, and compare their new notes. They are always surprised how much they discern on the second try. It's a lesson in "looking" versus "seeing", and how your brain trains itself to see something it is not accustoned to seeing. I've also done it a time or two with the moon, from about four days of lunation to about 3 days past full; then it's gone from the early evening.

Anyway, it's a good exercise to split the time at the eyepiece by five or ten minutes, if it fits in the time and population at the scope(s).

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Thanks Jim,

Keeping the educational content up while keeping the complexity and time required down is part of the exercise.

We had guests to dinner this evening, and everyone went out on the patio after dinner and set up for Saturn, several of the neighbors came over as well. We all compared observations at various magnifications. Tethys and Mimas were quite close early in the evening - we did resolve them at about 280x. We went all the way up to 533x, (3mm), but the 5mm (320x) was the best view of the night. Cassini division easily visible during moments of good seeing, and tracking the moons was a blast. We were even able to see some banding on Saturn - really good night!

Dan

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Hi Dan,

That is a good log sheet and i might have a dabble.

Just out of interest for anyone reading this thread:

One of my books say's that April is when Saturn will be putting on it's most magnificent display of the year, shining all night long at magnitude +0.6 in the constellation of Virgo.

On the 3rd of April, Saturn is at opposition, closest to our planet - a 'mere' 1290 million kilometres away - and opposite the sun as seen from Earth.

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Hi folks,

I've attached a scan of my own observation sheet from last night. I had the scope out on the front patio (too many lights, but that doesn't kill Saturn!).

Skies were quite clear (better than earlier this week) but much more turbulent than Tuesday. Seeing at high power was much more a "come-and-go" sort of thing. It made fine details like the Cassini division much more challenging!

Sorry the pencil sketch of Saturn isn't more clear - I increased the resolution of the scan from 300 to 600 dpi only to find that the file was too big!

Anyone else have results to post???

Dan

Saturn Observation 3-31-11.doc

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