Gruithuisen Domes 10 June 2014

[themos]

Hello all, 

After noticing that ISS was overhead at about 9:30pm, I checked calsky & Stellarium for the next pass. It was due around 23:03 and it looked like it was going to go straight in front of M51, the Whirlpool Galaxy. I wondered if it was going to be dark enough to see M51 at that time, with a 91% full moon up as well. My astro-buddy Clifford turned up for the stakeout. The 12-inch Dobsonian had cooled nicely for about an hour. It took us a little time to find M51, not having done this for a while. You find Alkaid (the last of the Plough handle), notice 24 CVn (mag 4.7), the next brightest star in the finder and center that. You then go "down and to the left" (angle 120deg, approx, SSW) for the same distance, to find M51. Couldn't see any nebulosity at that spot, but we could see what looked like a double star, the cores of the two galaxies in M51 (mag 8.4). We confirmed it by checking that 2 nearby  stars (mag 7) make a right angle triangle with M51. We had a 12mm Nagler on the scope, giving us a FOV of 0.64 degrees. The ISS turned up on time but, unfortunately completely missed the "target". Stellarium had it going 0.25 degrees off M51 and CalSky  was showing it as perhaps 1-2 galaxy widths away. Well, it wasn't!

And so we turned our attention to the Moon, which was only about 20 degrees from the horizon. On Monday, we had heard a talk at the Abingdon Astronomical Society about volcanic features on the Moon so we set about trying to see some of them. The Gruitsuisen Domes are near the Bay of Rainbows and they are about 30 and 20 km in diameter. We soon realized that the seeing was so exceptional we could up the magnification to 300x, using a 5mm orthoscopic eyepiece. Even at that power, I could not detect any rippling of the image from tube currents or atmospheric turbulence. We spent some time taking the views in, trying to spot smaller features on the domes. They certainly look dissimilar to other nearby features. 

So, when the Moon is messing up your deep sky views, have a look, you might be in for a pleasant surprise!

 

[michael.h.f.wilkinson]

Very nice shot!

[themos]

Very nice shot!

Gosh, it's not my shot! This was strictly observing! But it certainly was the night for imaging.