The Shadow Transit of Titan

I spent the early morning hours of Sunday watching an event along with three other members of the Amateur Astronomers Association of Pittsburgh. (3AP.org) Using the 115 year old, 11” Brashear Telescope at the Wagman Observatory, John Holtz, Mike Miller, Sean Matoon and I watched as the shadow of Titan, one of Saturn’s moons, crossed onto and across the planet’s surface. These transits occur about every 15 years.

    The astronomy club had two star parties this weekend and after the second one, after the public had departed, we aimed the telescope at Saturn. The seeing was pretty steady, the image wasn’t bouncing around at all and we had no problems increasing the magnification.

    Neptune was sitting within a degree or two of Saturn so we swung the scope over to it while we were waiting for the transit to start. The planet first appeared as a faint blue dot but by increasing the magnification we were able to see it as a round disc. We weren’t able to see any features on it. The shadow of Titan would be about 1/3 the size of Neptune, this could be difficult!

    As Saturn orbits the sun, our view of the planet's rings change. We recently passed through the ring’s plane where the rings appear to us as being edge on. This gives us a quite different view of the planet as to what we are familiar with.

Notesfrom a Reading Addict: Going, Going...

    When the planet is in this orientation, the shadow of Titan, the largest of the planet’s moons, can be observed crossing the planet’s surface. The moon orbits Saturn every 16 days so we have a chance to see this event a couple more times during the next month or two.

    Moving the scope back to Saturn and turning off all the lights in the room, we watched. Titan could be seen sitting below the planet’s rings on the right-hand side. The transit was due to start at 2:25 but we couldn’t see it until 2:30 when John first located it.

    Over the next hour and a half, we watched as the shadow slowly worked it’s way towards the meridian. We experimented with a variety of eyepieces, giving us magnifications between 243 - 939 power! While the viewing at 939X was nice, as would be expected, we opted for a lower power which gave us a much crisper image. We even tried using a binocular viewer which sadly, was difficult to use. It did give me a nice 3-D image of the planet!

    The shadow was dim and I had difficulty seeing it. The other three having much better eyesight could see the shadow much easier.

    We watched it, taking turns at the scope until a bit after 4 when we decided to close things up. Dawn wasn’t far away, our homes seemed even further. I pulled up in front of my house at 5.

    I think it was great seeing this. It is another astronomical event to tuck into my belt. It wasn’t quite as exciting as watching a solar eclipse or watching Mars slip behind the moon but it was right up there with them!

A Chance Encounter

 

        Clouds were drifting through the sky as sunset approached. Overhead I could see Vega. I had hopes for an eventual clearing…so I went to take a nap!

        Waking a bit after 11 I went outside to see a nice clear sky. Jupiter and Saturn were right in my “window”.  My front yard is framed by trees. Saturn was heading towards the trees to the west and Jupiter had just appeared out of the trees to the east. Best of all, most of the neighbors lights were off!

        I set up the scope and aligned the finder scope. My first observation was of Saturn. The image moved in and out of focus a bit as the telescope acclimated to the slightly cooler temperature. It settled down rather quickly and I was treated to a nice crisp, steady view of the ringed planet and its brightest moon, Titan. I was using a 12.5mm Coulter Optical eyepiece which gave me 12X. Before the planet slipped behind the trees I put a doubler on it for awhile.

        When I moved over to Jupiter, there were only three of its bright moons visible. I figured the fourth was either behind or in front of the planet Curious about where the fourth moon was, I consulted The Observers Handbook. I quickly found out that the fourth moon, Ganymede, was transiting across the front of the planet. Best of all, I saw that it was due to reappear in about 12 minutes!

        This is one of the reasons I like to have reference materials close at hand. I could’ve looked this up on the computer but I would have ruined my night vision in the process.

        I went to the telescope and put a Meade Ultra Wide 4.7mm eyepiece in the focuser. This gave me 32X.

        One of the first things I noticed was a sharp black dot near the center of the planets disc. Situated between the two darkest cloud bands, it was the shadow of Ganymede!

        I kept a close eye on the edge of the planet’s disc. As the time neared, (12:36AM) I started to see a bump grow. It increased in size until a little after 12:36, I could see a sliver in-between it and the planet.

        Not long after watching this, I started to tear down my set up. Jupiter was heading towards the trees and my scope was covered with dew. In all I had observed for a little over an hour and in that hour I had watched the universe in motion! As so often when observing you are looking at objects that are set in place. They are so far away you can’t see any movement at all except for the spinning of our own planet. Watching the transit of Ganymede was cool, happening upon it at the right time was lucky!

        After putting my equipment away, I went outside to check if I had left anything behind. The sky was starting to cloud over again. Seems I timed it just right! I returned to my bed because I had important dreams waiting for me!

        (Excuse my amateur drawings, they were taken from my notes)

P.S. The A.A.A.P. is scheduled another star party on September 11th, at the Wagman Observatory! You might want to mark that on your calendar!