Hello, one and all.
Wasn’t last great to meet up again at the Sugarloaf again after so long?
It was great to see Michael, Paul and Darren on Friday night 18th June 2021 with minimal wind and no dew happening.
I was delighted to do some more double star observing in the south-eastern area of Boötes the Herdsman with my William Optics 158 mm F/7 apochromatic refractor.
Even though the Sun refused to set until 9.56 pm, I managed to seek out some wonderful doubles in this area after 11 pm.
1. But before I describe them in detail, there was one other very bright orb in the sky. Many thanks to Michael for informing us what features were available on his laptop. The -10.5 magnitude, 57% illuminated, 8.3 day old slightly gibbous Moon was on view. Rupes Recta, Rima Birt, Montes Apennines, the craters Pitatus (with its central peak) Plato, Archimedes, Eratosthenes (and its central peak), Thebit, Deslandres, Hell, Lexell, Tycho, Moretus, Gruemberger and Birt were all observed. There was also a stunning event occurring also. The entire rim of Clavius, which has a diameter of 225 km, was fully visible and right on the terminator. Its very large centre was almost in complete darkness except for the satellite craters C and D. You can check out Map 72 in Rukl if you have it.
You can check out these double star systems on
www.stelledoppie.it
if you wish.
2. My first double was actually a triple: Pi Boӧtis (STF 1864). A & B may be an uncertain double and C is definitely an optical companion. It is one I had observed in the past and is very pleasant to the eye. Magnitudes: A = 4.8. B = 5.8. C = 10.6. Sep’s = 5.4” & 128.8”. PA’s = 113˚ & 164˚. A & B were almost split at 40X. But what a great sight was to be had at 112X. I figured A was blue. But B appeared orange. C was white. It was a perfect start.
These next 3 systems I have never observed before.
3. Further south and very near 31 Boo, we have STF (F.G.W. Struve) 1870 which is an uncertain double. Magnitudes: A = 7.5. B = 10. Sep = 4.8”. PA = 229˚. The primary appeared (F2) yellow-white. B seemed white. Quite nice and a good split at 112X.
4. STF 1873 is a true binary. Magnitudes: A = 8. B = 8.4. Sep = 6.9”. PA = 94˚. My scope achieved a very nice split at 40X. But at 112X I could certainly see the primary as a G5 yellow star. STF 1873 is a little cracker for sure.
5. Very nearby I found HLD 120 which is an optical double. Magnitudes: A = 8.1. B = 11.6. Sep = 15.7”. PA = 225˚. I had a very slender split at 40X which surprised me somewhat considering the secondary is so dim. But 112X was good to notice the orange colour of the primary. HLD stands for Edward Singleton Holden (1846-1914). He was an American astronomer and a university teacher.
6. The primary and the secondary of STF 1879 is a true binary. C is too faint for yours truly, but there is a D star and it is an optical companion. Magnitudes: A = 7.8. B = 8.5. D = 10.8. Sep’s = 1.7” and 120.4”. PA’s = 82˚ and 228˚. This truly was the main new showpiece of the night! My William Optics refractor was trying to split A and B at a mere 112X. However great joy was to be had at 140X. I had the slenderest of black gaps between the 2 stars. A was G2V yellow. B and C were white. I had one last look at STF 1879 at 167X, and it is a real winner indeed. Why not give it a go?
7. I finished off the night with Izar which was split at both 112X and 140X. Seeing conditions must have been very good once again.
Thank you for my reading my latest report.
Comments, corrections and images are very welcome.
Clear skies from Aubrey.
