Best because there were stars, it was mild, and I could stay out as long as I liked and sleep in this morning …
The worst of nights – well, it wasn’t actually, but the seeing wasn’t great, the collimation on the 10″ was playing up, and I got lost hunting for Uranus, so some parts were definitely maddening.
Uranus is now on the borders of Pisces and Aquarius with no very obvious star to take bearings from. I had a finder chart from Sky and Telescope but after half an hour of fruitless rambling I started Stellarium to try for a better clue, and this time located. Uranus is side-by-side with 44 Psc, an undistinguished star of about the same magnitude as the planet (five-and-a-bit), but luckily sitting in a fairly distinct pattern with its even less distinguished neighbour stars. Not that Uranus looked like anything much with the poor seeing/dodgy collimation – a small blob of turquoise fuzz.
During the small hours I concentrated on Jupiter as it rose above the trees. Io had been transiting the planet and was due to exit, and Europa was approaching transit from the other side, so I could look for Io, and also for Europa’s shadow preceding it on the disc.
Again, seeing not great, and although I could see dark features in the NEB and SEB it was difficult to get a real fix on their size and shape. Io was not visible until it was almost on the limb, but when you see it the whole system pops up into 3D. I don’t think I have seen Europa’s shadow transit before, and when I eventually saw the shadow it seemed very small and pale compared with what I’d expect Io’s to be like, but of course Europa orbits further from Jupiter so presumably the shadow isn’t so crisp on the cloud tops.
Drawings: South roughly at the top depending how cricked my neck was; Io, Europa’s shadow and Europa – direction of travel right to left.
This was about 02.25 UT this morning – Io about to exit to the left
And this was about 03.15 UT. Io is moving away to the left, Europa’s shadow has just passed Jupiter’s meridian, and Europa is approaching from the right.
In between drawings of Jupiter, I wandered the sky with binoculars and watched Gemini and Orion rise. Autumn is definitely here…