Observations - 3rd June 2021

Greetings, everyone, especially if you are a double star enthusiast. 

I had no idea we were going to have a remarkably good seeing night on Thursday 3rd June 2021. My Williams Optics 158 mm F/7 apochromatic refractor was placed in my back garden to observe these simple and attractive doubles and even some triples for good measure. 
This observing session commenced at 20.29 UT and finished at 23.00 UT which is midnight local time. Sunset occurred at 20.45 UT. The wind was 14 km/h quite a lot of the time. But was dying down all the time. Air temperatures decreased from 10˚ to 8˚ Celsius. 

Figures are from www.stelledoppie.it  

1. Where else to start in Boötes the Herdsman only with Arcturus (Alpha Boӧtis)? My Williams Optics 70 mm F/6 apo located it at 20.53 UT. That’s a full 16 minutes before sunset. I could see its golden hue fully at 40X in the main scope. 

2. Yet again I got a clean separation of Izar (Epsilon Boӧtis) at 20.53 UT at a magnification of 112X which was well before Arcturus was visible with my unaided eyes. The yellow-orange and blue colours were extremely good at 112X, 140X and 167X. It was at this point I was realising the seeing conditions were very good. 

3. It took a while to find Delta Boӧtis. It is a true binary with magnitudes: A = 3.6. B = 7.9. Sep = 105”. PA = 78˚. 40X was sufficient of course. A is yellow and B is grey. 

4. Mu Boӧtis (Alkalurops) is very close by. It is a true triple star system. Magnitudes: A = 4.3. B = 7.1. C = 7.6. Sep’s = 109” and 2.2”. PA’s = 172˚ and 2˚. It’s a real thrill to split the 2 yellow-white stars of B and C of course at 112X. The 2 companions point up to the brighter yellow primary. Superb views were had at 140X and 167X.

5. Up from Mu Boӧtis are 2 double stars which my scope can fit in the same fov and I have observed in the past. STF 1921 is the southern pair and it is a true binary. Magnitudes: A = 8.6. B = 8.7. Sep = 30.3”. PA = 283˚. There are 2 or 3 field stars between STF 1921 and this next double STF 1916. It’s a true binary also. Magnitudes: A = 8.4. B = 10.6. Sep = 9.8”. PA = 332˚. Both these doubles were easily split at 40X. And they are, give or take, half a degree apart. 

6. Back down I went to Arcturus to observe once again the true binary STF 1825. Magnitudes: A = 6.5. B = 8.4. Sep = 4.4”. PA = 153˚. Great split at 112X of course. But you can imagine my surprise when I put back in my 28 mm 2” eyepiece which gives 40X and notice I had the slenderest of separations at such a lowly magnification. It clearly was a night of extraordinary transparency.   

7. I then travelled north to a bright true binary called BGH 50. BGH stands for Sydney van der Burgh who was born in 1929 and could well be still alive. BGH 50 looks very fine in my WO 70 mm apo at 11X. Magnitudes: A = 7. B = 8.9. Sep = 7. B = 32˚. At 40X A is yellow-white and B is slight orange. It definitely is a good double for users of binoculars. 

These next 3 doubles I never observed before. 

8. STF 1808 is a true binary, but C is optical. Magnitudes: A = 8.8. B = 9.6. C = 11.8. Sep’s = 2.7” and 61.2”. PA’s = 83˚ and 109˚. Please don’t be so concerned if you don’t see C. Separating A and B is the main exercise. I achieved that at 112X. The view looked nice at 140X and 167X too. The primary has a slight yellow hue. 

9. Further we have a true binary called STF 1812. Magnitudes: A = 7.9. B = 9.5. Sep = 14.1”. PA = 108˚. Good clean split at 40X. The colours are yellow-white and white.

10. Just down a bit we have another true binary: STF 1810. Magnitudes: A = 9. B = 9.6. Sep = 2.4”. PA = 183˚. I had a delightful split at 112X. A is yellow. B is white. Not too difficult at all. 

11. And finally, I finish with a triple star which I have observed before. And strangely enough, no one on Cloudy Nights or www.irishastronomy.org has reported on it. But perhaps it is always possible some folk here have actually observed BU 1442. A & B are a true binary, but C is an optical companion and slightly brighter. Magnitudes: A = 9.9. B = 10.2. C = 9.7. Sep’s from A are 45.2” and 75.2”. PA’s = 74˚ and 61˚. The spectral classes are M1, M1.5 and K7. The colours I see are red, red and almond brown. I greatly admire the curved shape of BU 1442. It’s a splendid sight at 40X, 112X and 167X. So why not give it a try and report back please? Even users of binoculars (which are mounted) might have a go at observing BU 1442. 


Thank you for reading my latest report. 

As usual, comments images and corrections are very welcome. 

I wish you all clear skies, 

Aubrey. 
 

Hi Aubrey,

I hope you and yours are well. I very much enjoyed reading your observational report. It is amazing to think that you were able to find Arcturus and Izar so early in the evening. 

I love the name 'Alkalurops', so I had to find out a little bit more about it. I discovered the following: Alkalurops was the Arabian adaptation of Kalaurops, used by Hesychios (5th century. AD.) for the Herdsman’s Club, Crook, or Staff, analogous to the Ropalon of Hyginus and the Clava of the Latins. 

Thanks for bringing my attention to it! 

And BU 1442 sounds delightful...I must give it a go. 

Just looking out the window as I type this, and I'm considering setting up the scope. 

Clear skies, 

Darren. 


 

Hello, Darren. 
It's very great to hear from you once more. 
I find it fairly easy to find Arcturus before sunset as I have its position memorised at this stage when compared to my neighbour's house. 
Izar is much more difficult because it's fainter of course. 
In the past, I have observed both Arcturus and have had a separated Izar before sunset. 
I would love to do so again. 
But there is plenty of time to do so. 

I thank you very much for checking out Alkalurops. 
I had often wondered who did put a name on it. 
Some of those Arabs were very intelligent. 
By the way, I have checked the pronunciation of Alkalurops. 
Would you believe it is the 3rd syllable which get precedence on the other syllables. 
Very un-English, if you ask me. 
We normally emphasise the 2nd as we speak English if the word has at least 3 syllables. 

I appear to be the only observer who claims to be an ambassador for BU 1442. 
Maybe I'm a world ambassador for this enigmatic triple star 

At the moment my sky has plenty of medium height clouds. 
I hope you will get to see something, Darren -  if not over the weekend,    
I'm sure you're itching to see Epsilon Lyrae! 

Clear skies from Aubrey. 

Morning Aubrey,

Last night was a non-runner... The clouds wouldn't clear, however Met Éireann are forecasting clear skies from 11pm tonight 

Meaning, I'll be setting up my scope nice and early. And yes, I'll be going after the 'double-double' in Vega.

Very many thanks for letting me know about the pronunciation of that triple star... That could be on the cards for tonight too.

Here's hoping! 

All the best, 

Darren. 

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