Good evening, everybody.
It's great to see our favourite Irish astronomy website quite busy again in recent days.
I start by giving Michael a big thank you for encouraging Darren and me to get out of our homes with 3 fine telescopes for a little while on Friday night. Maybe more will attend next time! The car park beside St. Patrick's Church appears to be a very good observing area.
Anyway as you all know, I own a William Optics (WO) 158 mm F/7 apochromatic refractor and a WO 70 mm F/6 small apo which are both placed on a Berlebach Planet alt-az mount. 2" mirror diagonals are fitted to both scopes. Therefore my north is up, but my east is to the right.
It was all about 3 planets on Friday night 25th September 2020. But I also had a look at the Moon also.
I observed from about 8.15 pm to just before 11 pm. Sunset had occurred at 19.15 pm. The temperatures fell from 4 degrees down to 0 degrees Celsius during our time. The winds were brisk enough.
1. Where better to start than with Jupiter. Using the WO small apo at 11X the -2.4 magnitude disc was very bright of course. But I could make out on the east side 5.7 magnitude Europa, 5.1 mag Ganymede and 6.4 mag Callisto. Switching to the main scope then using magnifications 40X and 112X at 21.37 or thereabouts, a mag 5.7 Io appeared from behind Jupiter's shadow. All 3 of us let out a few roars as Io slowly brightened! What a magnificent sight it was. I did have the very same privilege about 8 or 9 years ago when I last observed Io doing precisely the same thing. It meant that all 4 moons were now on the east side of Jupiter. And all 4 moons are in the correct order in their orbits. Io having the closest orbit was a lot closer which was followed by Europa, Ganymede and Callisto. How cool is that?! I did not go higher in magnifications as the seeing was not great because of all the wind currents. For the record Jupiter was 716,000,000 kms from Earth and had an angular diameter of 41.2".
2. Next up was Saturn. Even at the considerably low power of 112X I could make out 8.6 mag Titan south of the beautiful rings of Saturn, mag 10 Rhea, mag 10.5 Tethys and 10.7 Dione which was between Rhea and the rings of Saturn. That's not bad: 4 moons at 112X with a noticeable wind. Right now the rings have a 23 degree tilt and they are closing a bit year by year. Saturn's magnitude is +0.4. Its distance was 1,433,240,000 kms from us.
3. Mars was affected by the less than reasonable seeing conditions too. Its magnitude was -2.4. Its distance was less than 63,350,000 kms from Earth. Its angular diameter was 22.1". But even at 112X I could make out the great dark area called Syrtis Major which is hugely famous. Mare Serpentis, Mare Tyrrhenum were quite easy to see also. Michael's image had those 3 features and also, I believe, he could see both Hellas and the South Polar Cap. Good catch, Michael!
4. Lastly I should say something in regards to the 8.5 day old Moon which I observed at a mere 40X. Straight away all 3 of us saw Rupes Recta in our own scopes. The 3 craters Plato, Archimedes, Eratosthenes and the Montes Apennines were all on view. However I was looking around for the crater Tycho. Where is he? But there he was right on the terminator! The centre of the 65 km crater was in darkness, but its complete rim was catching the Sun's illumination. There were no rays or central peak on this particular Friday night. I don't remember seeing the crater this way before.
Thank you for reading.
The 3 of us had great craic. And seeing Darren's new car and his 10" Dobsonian. Michael's C11 with his very good imaging system and laptop was a real bonus - especially when he zoomed in on Albireo.
Tomorrow I will do another report on what I observed on Saturday night 26th September.
Best regards from Aubrey.
