2006-06-28

Area 897 was more spread out when compared to yesterday (hardly surprising given that it has rotated further into view) and I could count 5 spots in the region. The darkening I noted yesterday wasn't evident today.

New area 898 has come over the limb and comprises of a single, large, circular spot with quite a pronounced penumbra.

Started out with the 905 and 6mm eyepiece. The image was awful. I could only just see the two main bands. The reason for this was probably down to the quality of the sky and also down to the fact that the 'scope hadn't had much time to cool down yet.

I could see all 4 Jovian moons (one of them was very close to the planet) and I could also see a reasonably bright background star that could have been mistaken for a 5^th moon (later checking with Starry Night showed that it was HIP70714 ).

I then added the #80A Medium Blue filter to the 'scope and had another look. While this dulled the image a little it did also appear to improve the contrast. The two main bands stood out a little better, darkening towards the poles became obvious and in moments when the image was steady there was obvious mottling in the bands.

I'd say that tonight's view of Jupiter is the worst one I've had this apparition.

I've never compared the view of Jupiter in the 130M with that in the 905 so, at around 21:53 UT, I brought the 130M out and left it to cool off. A short while later (probably with too little cooling-off time) I lined Jupiter up in the 130M and used the 6mm eyepiece to have a look. The imagine was really terrible — much worse then the image in the 905. While the view was much brighter there was hardly any detail to speak of, almost as if it was impossible to get sharp focus.

I switched from the 6mm to the 10mm eyepiece and things looked a little better. This time the quality compared more favourably with that as seen in the 905+6mm but, even then, I'd say that the 905 won out in terms of detail that could be seen. It would appear that I need to give the 130M a good check-up at some point. While I did give the collimation a quick check when I brought the 130M out I guess I need to have it a really fine tweak some time soon.

I'm also seeing why planetary observers tend to prefer a refractor rather than a reflecting telescope.

Back at the 905 (with the 6mm), at around 22:19 UT, I noticed that the moon closest to Jupiter had apparently got even closer. Compared to when I started observing this evening it was harder to see it, the gap between it and the planet being obviously narrower. I stepped into the office to check what was going on and I confirmed that the moon was Europa and that it was due to start a transit of the planet at around 22:38 UT. My first ever transit of a Jovian moon! Annoyingly, when I came back out of the office, I noticed that some thin cloud had moved in the way and was dulling the view of Jupiter.

By 22:31 UT the image had improved again. I could just see Europa but it was impossible to see a gap between it and the planet — it looked more like a bump on the limb.

By 22:36 UT I had lost sight of Europa. From then until 22:59 UT I kept observing to see if I could detect Europa in front of the planet but I never got a hint of it. This was made harder by the fact that more thin cloud was moving in the way and significantly dulling the view.

To finish off the session I decided to use the 905 for one of the main purposes I intended: just sweeping around the sky and seeing what I can find. Using the 32mm eyepiece I started to have a random sweep and, almost right away, stumbled on The Coathanger (an asterism I first observed almost a year ago).

After spending some more time just sweeping around (mostly around The Milky Way in and around Cygnus) I decided to call it a night at 23:34 UT.