Rhea what an awesome sight.

[Doc]

Set up scope tonight as it looked pretty clear and saw a fantasic sight that I haven't seen before let me explain....

I was observing Saturn about 20.30 and could clearly make out Titan at 8.4, Tethys at 10.3, Dione at 10.5, Encelade at 11.8 and along way out was Lapetus at 11.2.

While watching these Rhea started to emerge from behind Saturns limb at 20.40 . At mag 9.8 and only 949 miles in diameter I was amazed that I could clearly define the emergence and clearly see a dark gap between Rhea and Saturn. I observed for a good 10 minutes until Rhea was well past Saturns edge.

I don't know if there is a correct term for this emergence of a moon behind it's parent planet but it's the first time I've observed it.

Anyway clouds started to roll in after this and they looked thick enough to settle in for the night so packed away the scope.

[Talitha]

:hello2:Nice going, Mick! Was the seeing a bit better than average? Splitting doubles is always easier when it is, and you can't get a bigger variance between a primary and a secondary than there is with Saturn and Rhea, lol. (The terms are 'ingress' and 'egress', btw.)

[Doc]

Ingress and egress thanks Carol.

So I persume Rhea was egressing at the time.

[irishbloke]

I have been hoping to manage the same thing. I'd love to see a transit too. I have a skywatcher 250px dob, 8 and 17mm hyperion eyepeices and a Philips spc900 webcam. I am wondering if i should be able to see visually a transit or is the web cam the best route as I can control the gain.

Also how much does the darkness of site affect my chances. Are filters any use in this quest.

Thanks Mick for the inspiration to keep trying!

Brian

[Talitha]

Yep, it was egressing after being occulted by Saturn.

(Take notes, there'll be a quiz at the end of the week, lol.)

[Doc]

Thanks Carol I'll make sure I revise

Thanks for the kind words Brian. I have never seen a transit either, it's on my list though.

As for my skies well they are not dark thats for sure but whats important is a good quality eyepiece and a high magnification. I used a 12.5 mm orthoscopic and it worked really well.

[JDC_MBA_PHD]

Hi:

I found Rhea to be at about the limit of what I could photograph with a webcam last year.

I also, just for the sheer heck of it, tracked its orbit, measuring its position at various times. This is what I found. You can get amazingly accurate measurements of the orbital period - this one is only about 0.04% different from the Wikipedia value.

Regards,

John.