Vesta is one of the brightest asteroids, easily visible with a pair of binoculars. On July 16, NASA’s Dawn spacecraft went into orbit around Vesta and began sending close-up images.
Last night, I searched for Vesta, which was low in the south, at an altitude of about 20 degrees, between some Douglas fir trees. If it hadn’t been for the tree cutting of some red alders for firewood last year, I wouldn’t have been able to catch Vesta at all. It was predicted to reach its highest point in the sky at 2:10 am this morning, so I decided to start imaging then.
Using the planetarium program, TheSky6, to find it, I thought I knew where to look. But alas, it wasn’t where the program said it would be! Then it dawned on me that maybe I needed to update the orbital parameters for the asteroid, as there must be better numbers available now than there were when I first installed the program. I then found the personal website of Marc A. Murison which includes a calculator of asteroid orbital parameters.
Just what I needed! Putting the new numbers into Vesta asteroid data of TheSky did the trick. The telescope went directly to the target. But it was still behind the trees, so I had to wait about half an hour. Fortunately I had Mr. Murison’s blog to read, which has some great political commentary and kept me awake.
I then started a sequence of images (10s exposure, clear filter, ST-8 camera, Takahashi FSQ-106 telescope) and went to bed for a couple of hours.
When I got up to check my images and close down the observatory, I discovered that there were about 40 minutes of good images, unblocked by trees. So I put together the following animation, in which successive frames were about a minute apart.
In just 40 minutes, you can clearly see the asteroid moving relative to the background of stars.