Jupiter and the Asteroid Impact Site

Date: 2009-07-22
Time: 04:33 UT
Location: Snellville, GA
Telescope: 10-in Dobsonian f/4.5
Magnifications: 44x, 110x
Object: Jupiter
Seeing (scale 0--4) Started out at 1 and worked it's way up to 3.
Atmosphere: Light clouds. Cool air for the summer.

I'm entering these notes nearly two days after the observations.

I started observing before the telescope had come to temperature. Also Jupiter was quite low in the East so, from at least those two factors, the seeing was quite terrible. The four Galilean moons were dancing sparklers and it was very difficult to see any detail on the planet other than the main belts.

I'll include the tweets I made at the time.

Observing Jupiter. 10-in f/5.4 Dob, 110x. Seeing is terrible, 1 (0--4). SEB and GEB easy but no GRS or impact site.12:33 AM Jul 22nd .

As the planet rose higher and the telescope settled down, the viewing was much better. I was easily able to see the North Equatorial Belt and the North Temperate Belt (NTeB). The South Equatorial Belt (SEB) was also easily divided into it's two parts.

Seeing is better, 3. Tel has settled down and planet is higher. NEB a d belt just north easy. Still no GRS or impact.12:47 AM Jul 22nd

I couldn't see the GRS, Great Red Spot (hollow), at all though it may have rotated to the limb at the time.

As the seeing improved, the four moons became tiny disks. One was leading (Io) and three following (Ganymede, Europa and Callisto from west to east away from Jupiter). The identification is based on Sky and Telescope's moon Javascript program.

For much of the time I used the 3.5-in aperture stop which makes my Newtonian an f/15 unobstructed off-axis telescope. Most observing was done at 110x.

By 5:00 UT thin clouds covered the planet but I continued to observe through them. They mainly just attenuated the brightness.

I was never able to resolve the impact site. It should have been there but at this magnitude, with the seeing and maybe my eyes, I couldn't resolve it. I could see a lot of belt detail and could see the belts including the dark higher latitude belts in the South.

I can see excellent belt detail but no impact site visible in North. Maybe it's smeared?1:01 AM Jul 22nd

Well I don't see it. The SEB appears split in two. I can see the faint belt N of the NEB. But no impact site.1:19 AM Jul 22nd

I stopped observing sometime around 5:19 UT.

Reference: Sky and Telescope Jupiter Observing Guide