2007-05-22

Lunar Occultation of Saturn

Tonight I was lucky enough to observe the lunar occultation of Saturn.

Skies were nice and clear for me when I got the Explorer 130M out at around 18:45 UT. By 18:51 UT (yes, no time to let the 'scope cool down) I had Saturn in the eyepiece. This in itself was a first for me. The Sun was still above the horizon — that's the first time I've observed that planet during the day.

The view kept switching from being very hard to make out to being very clear, sometimes clear enough that I could just about make out the planet's shadow on the rings.

The dark limb of the Moon wasn't visible at all so I had no visual clues as to how long I had to wait. There were a couple of false starts where I thought I could see part of Saturn was missing. And then, suddenly, it was really obvious that the Moon was cutting into the rings.

Sadly I didn't have a stopwatch with me so I had no way of timing how long the event took. It felt like it was over in about 30 seconds. I know I was very surprised at how quickly it all happened. It was all over by 19:06 UT.

And then I had a break. I had about an hour to wait until Saturn emerged.

Fast forward to 20:00 UT and the Moon was lost behind a load of cloud. I could see, towards the western horizon, a gap, but I didn't hold out much hope for it getting into place in time. For a while all I had to look at was:

Waiting for the Moon and Saturn
Click for larger picture

Finally, at around 20:12 UT a gap in the clouds gave me a view of the Moon but, just as quickly, it went again. By 20:13 UT a bigger gap moved into place and, through the 130M, I could already see Saturn. Part of the rings was still behind the Moon and over the next couple or so minutes I watched it fully emerge (Saturn was free of the Moon by 20:14 UT).

I just watched the gap between them widen for the next couple of minutes and, then, in a moment of madness (not the first moment of madness like this), I grabbed my mobile phone and held the camera in it up to the lens of the 'scope. This is what I got:

Moon and Saturn on Mobile Phone
Click for larger picture

Probably the worst occultation picture you'll see over the next few days. Probably the worst occultation picture you've ever seen and will ever see. But, what the hell, it had to be done. :-)

By 20:19 UT it had clouded over again. I left it a short while longer and then, realising that was it, I packed up.

I'm so glad I didn't miss it.

7 comments:

James said...

At least to the knowledgeable observer it's clear what is happening!

Not the best, but certainly not the worst :)

Dave Pearson said...

Heh. I did have a friend, who will admit that he's not knowledgeable about these things (and is probably reading this and will be along to confirm this any time soon), go "so the blue circle is the Moon?" :-)

Tag said...

Have been reading your report, along with others, about this event. A surprise since I was completely off guard. I think I'll stroll through SPA via you link to see if there are more reports.
Similarly, I take for granted when showing the Sun that folks will immediately recognize that the whole disk _is_ the sun.
peter

Dave Pearson said...

This thread has a few reports, most of them short and to the point (some even made during the event).

Also, if you look in the gallery you'll find various images from the occultation too.

It's a good point that you make about people appreciating what it is they're seeing via the eyepiece. I hadn't thought about it before but, yes, I can imagine that showing someone the Sun via a 'scope could actually be quite confusing.

Tag said...

Thanks for the links.

Funny, Joe gets an eMail, "You sad muppet". Some great dialog and photos in the Gallery, not to mention Peter Lawrence. My first exposure to his work via recent discovery through yours and Stuart's site.

Dave Pearson said...

Yeah, Pete does some astounding work. The projects of his that I really like are the ones whose point is more than just capturing an image (such as the shadow of Venus project).

Ian Musgrave said...

I like the mobile phone images. There's something undefinably endering about them. Fantastci that you got to see the occulatation. The first decent planetary occulation I saw was Jupiter, and that was awesome, Saturn would be so much better, and I can't wait to get one doen here. Thanks for the gallery links!