Hello friends.
It was touch-and-go if I should set up my William Optics 158mm f/7 apochromatic refractor in my back garden on Friday night 24th June 2022. I just wasn’t sure if the skies were going to remain clear until about midnight. Sunset these nights occurs at 21.57 Irish Summer Time. Plus there was a 20km/h wind blowing. But the air temperatures were nice though - 12˚ Celsius. So I took the plunge and started setting up my scope from 21.30 Irish Summer Time (IST). I'm so glad I did! As ever I have mirror diagonals fitted to my main scope and the William Optics 70mm f/6 small apo which I use as a finder scope. This means my north is up but east is to the right.
These double stars’ figures can be checked out on
www.stelledoppie.it
1. I had memorised where the position of the gold star Arcturus roughly ought to be. And at 22.12 IST I found it in the 6˚ fov at 11x in the 70mm apo. It was a nice sight in the main scope at 40x. Its gold hue was a delightful sight to behold so soon after sunset. Then I had considerable problems with thick cloud. But the southerly wind was moving the clouds along very nicely.
2. In the meantime I took a look at Polaris in the northern sky; and amazingly Polaris B was visible at 112x in the 8 o’clock position. Otherwise known as a true binary STF 93 has magnitudes: A = 2.0. B = 9.1. Sep = 18.4”. PA = 236˚. A is F7 (yellow-white). B stays white for me.
3. The skies cleared soon after 23.00 IST. Izar (STF 1877) was tightly separated at 112x. Magnitudes: A = 2.6. B = 4.8. Sep = 2.9”. PA = 347˚. A had its familiar yellow-orange hue. But B is still white to this eye. Lovely split at 140x too.
These next 2 doubles are first time observations for yours truly. But there are goodies.
4. STF 1858 is a true binary and is listed in Robert Burnham’s Celestial Handbook. Magnitudes: A = 8.1. B = 9.0. Sep = 3”. PA = 38˚, I found the single star at 40x at the apex of a 4 star asterism that is shaped as a sideways V. So I knew I was in business. At 112x I had a beautiful double. I admired it so much I increased my magnifications to 140x and then 167x. What great joy I experienced at these 2 stunning stars that were nearly in a north-south direction. I wrote in my diary “what a little smasher STF 1858 is!” As you all know by now STF stands for Friedrich Georg Wilhelm von Struve (1793-1864). I thought that the primary was pure white; but the secondary had a slight orange tinge at 167x.
5. Less than 2˚ south of STF 1858 is HJ 554. It is a true binary also. Magnitudes: A = 10.4. B = 10.7. Sep = 11.7”. PA = 292˚. As you have figured out HJ 554 is seriously faint and my sky was still quite bright even at 23.30 IST – although Arcturus was easily visible with my eyes. However I needed 112x to see these 2 stars side by side at first. It was then I was noticing a colour with the primary. Its spectral class is K0. Therefore I increased once again up to 140x and 167x and could easily see its orange hue. Very nice! The secondary is a simple white and that’s okay. But I didn’t finish at that point. I wanted to see if I could see these 2 stars at the lowly power of 40x. And after some period of time, lo and behold, I had them! I then began to wonder what John Herschel (1792-1871) thought when he discovered this faint binary. Maybe he was as excited as I was when he first observed this very enchanting double called HJ 554.
That’s it from me. My observing session ended at 23.45 IST. Cloud had stopped proceedings and it actually started to rain as I was finishing up putting everything away. But my scopes were back in the garage by then.
Comments and images are very welcome.
Clear skies from Aubrey.
