Observations - 8/12/22

Hello everyone.

I had a very clear sky as I was setting up my William Optics 158mm f/7 apochromatic refractor on its Berlebach Planet altazimuth mount at about 4.30pm on Thursday 8th December 2022 in its usual spot, i.e. the back garden. I also had my William Optics 70mm f/7 small apochromatic refractor fitted. I use this scope as a finder. The magnification is set at 11x and it gives me 6˚ fov. I do have a mirror diagonals placed on both scopes at all times.
There was a slight 10 km/h breeze and the air temperatures were a freezing minus 2˚ Celsius. By 8.30pm it was minus 4˚ Celsius. So I was wearing multiple layers of clothing.
My wife and I had dinner then.
www.met.ie warned me that snow was due my 9pm, and they were 100% correct! But by then, I had put everything back in the garage. 

I took my time observing these few objects. Sure - what’s the rush? Most of these celestial gems are in Cassiopeia, but 2 are in the adjacent constellation of Ursa Minoris. 

All double stars’ figures can be checked out on the website: www.stelledoppie.it  

1. And so - where better to start than with Polaris? It’s also called Alpha Ursae Minoris and STF 93. It has other names to, e.g. the North Star and 1 UMi too. Magnitudes: A = 2. B = 9.1. Sep = 18.4”.  PA = 236˚. What I find particularly interesting is that the positioning of the secondary is pointing straight up at 12 o’clock every December from Ireland. It’s also a test to see the companion at 40x. But I did see it this time at that power. Of course at 112x this true binary looks delightful. The primary has a good F7 yellow-white colour. The secondary seems to be a white star. 

2. I was surprised to note that there is a nice single star directly to the right of Polaris from my vantage point which I have never observed before: Lambda Ursae Minoris. Its magnitude is 6.4 or 6.5, so it is visible at minimum magnification at 11x. The spectral class is given as M1 on Simbad, and I found it to have a rather nice orange colour at 40x, 112x and 140x. It’s not a carbon star – mind. 

3. One keen observer on www.cloudynights.com has been very keen for us to observe the true binary STF 191 recently.  So, having printed off a “Portrait” map from my Guide 9.1 DVD, I crossed over the Ursa Minor border into Cassiopeia. I found this route very handy using my map. Having found the 5.3 magnitude star 47 Cassiopeiae and the brighter 4.5 mag star 49 Cas with my WO 70mm, both these stars were nearly pointing at STF 191. The magnitudes are: A = 6.2. B = 9.1. Sep = 5.3”. PA = 196˚. I saw no secondary at 40x as it is too faint and a bit too close to the primary. But what a transformation at 112x! The super little secondary was easily visible and still good and tight. It also looked wonderful at 140x. I recommend STF 191 to you all. It is listed in Burnham and Haas’ books. 

4. Seriously close by is a very dim optical double called STF 184. Magnitudes: A = 9.7. B = 10.7. Sep = 17”. PA = 14˚. I had no difficulty seeing a good separation between these 2 stars at 40x. At 112x I could see that the primary was F8 yellow-white. B is white. My 8mm eyepiece gives me 140x, but it does have a poor fov. However I was pleased to see both STF 191 and STF 184 in my same fov.   

5. Further south, Iota Cassiopeiae could not be ignored on my map. I have observed this quadruple star a number of times over the years. A & B are a true binary, but the C and D stars are optical companions. Magnitudes: A = 4.6. B = 6.9. C = 9.1. D = 8.5. Sep’s = 3”, 6.7” and 210.9”. PA’s = 228˚, 117˚ and 60˚. At 40x, I could see stars A, C and D. But what a stunning sight I always get at 112x. A & B are split. Each star is white. Some have said that Iota Cas is the finest multiple star in the entire sky. Certainly as a triple it could well be. 

6. But I would beg to differ! Psi Cassiopeiae’s companions are probably optical to the brighter star, but that doesn’t deny it is a beautiful triple – especially since the primary is a rather charming K0 yellow-orange star. B is too faint for my scope. So I’m left with A, C and D. Magnitudes: A = 4.7. C = 9.2. D = 10. Sep = 20.3”. PA = 128˚. The C & D stars are a true binary and they have their own designation: STF 117. Their separation is 2.9”. PA = 253˚. What a gorgeous sight I see at 112x! The C & D stars are so faint and yet so visible and separated. I also used 140x on this magnificent triple star. 

7. I spent some time observing the -2.5 magnitude planet Jupiter at a later stage. At 40x the 4 Galilean moons, Europa & Ganymede were positioned on the western side. Io & Callisto were on the eastern side. There was a magnitude 9.0 star that has the designation HD 224510. It was 1.5’ south of Callisto. It seemed this star was acting like a double star and a 5th moon of Jupiter. At 167x I observed a slightly dark Great Red Spot. I saw that the North Equatorial Belt was still darker than the South Equatorial Belt. The North Polar Region was easy to see, but there were only glimpses of the South Polar Region and the South South Temperate Belt. Sadly Jupiter disappeared behind a neighbour’s tree when the shadow of Ganymede was due to transit at 8.40pm. I have seen one of these before, but not for many a year.   

Thank you for reading my latest report. 

Comments are very welcome. 

Let’s hope for warmer conditions for the next time. 

Best regards from Aubrey.