Observations - 16/04/20

Hello, everyone – especially if you are a double star admirer.

I feel I should inform you about a double star I observed on Thursday 16th April 2020. I am including it at the end of this report.

But permit me to deal with other issues first.

The seeing conditions have been quite bad in recent weeks in around Dublin. And I have just discovered the reason why today. Venus has been positively shimmering any time I have observed it. It turns out a crime has been occurring up in the Wicklow mountains. There have been terrible gorse fires. Perhaps in due time when these fires cease we will have skies with much improved conditions..
Also on Thursday night I did endure very high cloud over me and my William Optics 158 mm F/7 apochromatic refractor. Even at 112X Venus was appalling with so much “boiling” going on - even before sunset.
As nightfall has been happening, it made no difference; and thick high cloud was arriving from the Irish Sea on this Thursday night. So my time of observing was cut short. However I did have very pleasant views of Algieba and Regulus.

Here are the details:

1. Venus is now less than 80 million kilometres from Earth. Her angular diameter was getting larger: 31.3”. She was 36.6% illuminated. The only detail I can give is that she was a thick crescent. The feminine planet is currently placed in a void section of Taurus. There were no stars near her. But with all the shimmering going on, it was time to move on. We can only hope those Wicklow fires will end soon – especially as Venus becomes a thinner and larger crescent.

www.stelledoppie.it supplied the figures to these doubles.

2. Algieba is a true binary and a glorious one. Magnitudes: A = 2.4. B = 3.6. Sep = 4.7”. PA = 127˚. Easily split at 112X, but with some shimmering of course. The colour of both stars are truly amazing. To my eyes, they are mostly yellow but with a good tint of orange. Both stars spectral classes are K0III. Do treat yourselves to this wonderful binary before our summer starts.

3. With a lot of cloud appearing I just wandered around the sky for a while figuring out what to look at next. I observed Castor and its 3 companions. Polaris was good too. It was split at 40X and at 112X. A is yellow-white (spectral class F7) and its companion is white. Magnitudes: A = 2. B = 9.2. Sep = 18.4”. PA = 236˚. At this time of year B is in the 6 o’clock position – charming.And it is a true binary.

4. I turn the clock back every time I observe Mizar and Alcor. This quadruple set of stars I first observed in 1977 as a teenage boy. It is still utterly magnificent! Magnitudes: A = 2.2. B = 3.9. D = 7.6. C = 4. C is Alcor and further away than D. The separation from A to B is 14.4”, Mizar and Alcor’s separation is 707”. A to D’s separation is less at 492”. So it is simply stunning to see all 4 stars at 40X. On this occasion I refused to go higher; the view was so splendid.

5. Gaps were occurring in the southern part of the sky. So I split 38 Lyncis yet again at 112X. Then I headed to the north western sky quite a bit north over the setting Venus. I had been planning to check out some doubles for the first time in Lynx. It’s easy to forget that this constellation is very wide. I have since discovered it is some 40˚ wide. The cloud that had been covering the eastern and the southern sky was now moving to the western sky. So my observing time was being cut short. But I did succeed in finding a delightful double star before I had to end this session.

6. But before I inform you of it, there is one other uncertain double I did succeed in finding and its designation is ES 2623. It's not a stunning double by any means. Magnitudes: A = 8.6. B = 11.5. Sep = 9.4”. PA = 320˚. As the sky was particularly bad at this point, it was very difficult to spot that dim 11.5 magnitude secondary. However I did spot it at 112X, 140X and 167X. But it did disappear from time to time. Of course no fancy colours were seen; A is plain white. B is a tiny dot. I wonder what Mr. Espin thought of it after he discovered it.

7. But my final double is extremely good. 20 Lyncis is a true binary. Magnitudes: A = 7.5. B = 7.7. Sep = 14.9”. PA = 256˚. So there is hardly any difference in their brightness. Of course it is effortlessly easy to split at 40X. But its spectral classes are A6 and F0. I was very charmed by the colours: a fine blue-white and yellow-white. Intensely beautiful at 40X and even better at 112X. The 2 stars point downwards to the north western horizon. It definitely will receive a visit from me when the skies clear again - a marvellous sight.

I should say that there are a few more doubles very nearby 20 Lyn. I had planned to study them, but the cloud prevented that possibility. Maybe next week we will have clear skies at some stage.

Thank you for reading my latest report.

Comments are very welcome as always.

Clear skies to you all from Aubrey.

Hello Aubrey,

Very many thanks for sharing your observations with us. Also, you've made an excellent point about the gorse fires up in the Wicklow Hills, and how they may impact on our observations. I watched the reports on the 9 O'Clock news this evening, but did not join up the dot until I read your post. So, thanks for that!

Mizar and Alcor are stunning, and are always impressive - beautiful objects! I have yet to view the other stars you mention, but as always your vivid descriptions provide all the inspiration that one might need to take a look at them.

Clear skies,

Darren.