Hello my double star friends.
I was noticing I was going to have very clear skies on Wednesday night 15th June 2022. So I pumped myself up and decided to place my William Optics 158mm f/7 apochromatic refractor with its small WO 70mm f/6 apo attached. But I fully recognised that the double stars I had presented myself were seriously close to the zenith. Therefore I lengthened the tripod legs to a much higher position. This meant my focusing knobs wouldn’t collide with the Berlebach Planet alt-az mount. It worked!
You see, my doubles were all in northwest Boötes.
Sunset occurred at 21.54 Irish Summer Time.
There really was no wind; and the air temperature was 16˚ Celsius.
The first stars were refusing to appear with my unaided eyes until shortly before 11pm.
So not much time to split the following systems as I had promised to stop observing at midnight. Because of mirror diagonals my north is upper left and my east is upper right. Time to put the skates on!
I have 6 Struve doubles for you all. Facts and figures are, as ever, from
www.stelledoppie.it
1. I starhopped from 1.9 mag Eta Ursae Majoris (Alkaid). Then straight up north to a rather famous double – double. The first, which was on the left, was Kappa Boӧtis. This double has the alternative designation STF 1821 and it is a true binary. Magnitudes: A = 4.5. B = 6.6. Sep = 13.8”. PA = 235˚. I was welcomed by the beauty of STF 1821.
2. Immediately east (to the right) of Kappa Boo is Iota Boӧtis. It is otherwise called STFA 26 and is also a true binary. Magnitudes: A = 4.8. B = 7.4. Sep = 39”. PA =33˚. With my 28mm 2” eyepiece 40x it’s a wonderful sight to see these extraordinary binaries separated and placed side my side when they are so close to the zenith.
These next 4 systems I have never observed before.
3. North of 4.2 mag Lambda Boӧtis is a dim optical double called STF 1826. Magnitudes: A = 8.9. B = 9.7. Sep = 4.5”. PA = 310˚. I was greatly surprised to notice that the 2 stars were trying to split at a mere 40x. Of course 112x did this double justice. I could see that the primary was F8 yellow-white, I also thought the secondary was slight blue.
4. The A & B of STF 1843 is a true binary. C is optical. Magnitudes: A = 7.7. B = 9.2. C = 9.7. Sep’s = 19.8” and 100.8”. PA’s = 186˚ and 63˚, There was no hassle seeing all 3 stars separated at 40x of course. But I thought I should check out the colours as there are interesting. A is definitely F4 yellow-white and C is G5 yellow okay. According to Simbad B’s spectral class is F5. As I increased to 112x I thought it had a slight orange tinge rather than a simple yellow-white. If others decide to study STF 1843, please feel free to come back to me regarding its colours. Thank you!
5. STF 1834 is a true binary for sure. It has a Grade 3 orbit and is slowly widening year after year. Magnitudes: A = 8.1. B = 8.3. Sep = <1.65”. PA = <104˚. I was on tenterhooks as to what magnification I would need to separate STF 1834 although I knew I would win at some point. So the good news is I could see the 2 stars touching at 112x. But grand success was to be had at 140x. And what a beautiful sight it is! The primary is yellow-white the secondary is white. STF 1834 was the showpiece double of the night.
6. Midnight was closing in on yours truly. I had one more faint double to seek out. STF 1806 is a true binary. Magnitudes: A = 10.1. B = 11. Sep = 13.1”. PA = 173˚. I had no problem separating this double at 40x – even though both stars were so faint. At 112x I noticed that the primary was F8 yellow-white. The secondary was white.
There were other doubles in the same area; but I had great difficulty seeing the secondary of BU 715 which is very near STF 1834. So I decided on not chasing even more difficult ones. Maybe if the sky had been darker I would have had better success with BU 715.
However I was very pleased with my one hour observing session.
Thank you for reading my report.
Comments are, as always, very welcome.
Clear skies from Aubrey.
again. 
