Hello everyone.
At last here is my promised report.
I was very pleased to notice I had a clear night with little wind (8km/h) during the early evening on Monday 2nd January 2023. The air temperatures were 6˚ Celsius, but it felt a lot colder. However it was my second clear night in a row to do some nice observing.
Before I headed up to Cepheus, I spent some time observing Jupiter with my William Optics 158mm apochromatic f/7 refractor on its Berlebach Planet alt-az mount and the WO 70mm f/6 small apo I use as a spotting scope. As usual I had my mirror diagonals fitted on both scopes.
1. Jupiter’s magnitude has now faded a little to -2.4. Its distance was a little less than 753.500,000 kms from Earth. Its angular diameter was a little more than 39”. I had started observing the giant planet at 16.15UT and finished with it at 17.10UT. Callisto, Europa and Ganymede were on the western side. Io was on the eastern side. At 112x I saw the Great Red Spot on the central meridian straight away. At 167x I could see its now familiar salmon colour. Jupiter’s largest moon Ganymede (mag 5.2) was closing in on Jupiter after 17.00UT. Then at 17.08, right on schedule, Ganymede was no longer visible. It had disappeared behind the planet from my view. Great start! How handy
www.skyandtelescope.com
is on getting the positions of Jupiter’s moons.
Then it was off to King Cepheus. These doubles’ figures can be found on
www.stelledoppie.it
.
Some of them I have observed before of course. With my mirror diagonals fitted my north is to the left, and my east is upwards.
2. Having separated Polaris yet again at 40x and 112x, I headed over again to observe Beta Cephei (Alfirk). Magnitudes: A = 3.2. B = 8.6. Sep = 13.5”. PA = 251˚. Good tight split at 40x. The secondary was in the 4’clock position.. Slightly defocusing both stars at 112x, I noticed that the primary has a slight blue-white B1 colour. The secondary is a definite stronger blue. These 2 stars are moving in space side by side. So it’s a relfix double.
3. Nearby is Mu Cephei – the Garnet Star. Its magnitude varies from 3.6 to 4.2. It’s so easy to see at 11x with my small apo. This time I used 40x, 112x, 140x and 167s. The garnet colour got stronger and stronger the higher I went. Mu Cep’s spectral class is M2 and it is a hypergiant star.
4. But what’s this? There is another M2 garnet star 5˚ north (to the left) of Mu Cephei. I have never observed VV Cephei before. It’s very easy to find with my small apo again at 11x. But to admire its own garnet colour I observed it at 40x, 112x 140x and 167x. It’s not as bright as Mu Cep, but it’s still worth checking out. Its magnitude varies from 4.9 to 5.4. One observer on
www.aavso.org
has estimated its magnitude as 5.2, and I would definitely agree. There are 3 lovely stars curving down to VV Cep and they are roughly as bright as VV Cep.
5. A keen double star observer on
www.cloudynights.com
asked me to observe the nearby true binary Xi Cephei (Alkurhah). Magnitudes: A = 4.5. B = 6.4. Sep = 8.1”. PA = 274˚. What a beauty it is! Even though I did split it before some years ago with this same refractor, I separated it and got the teardrop effect at 40x. The primary is A3 white. The secondary is blue-white hanging directly downwards. It also looks extremely good at 112x, 140x and 167x.
6. Less than 2˚ of Xi Cephei we find another true binary, and a rather nice one too: HJ 1713. (HJ stands for John Herschel). Magnitudes: A = 8.7. B = 10.7. Sep = 18.7”. PA = 125˚ (1 o’clock position). I could split Xi Cep and HJ 1713 in the same fov at 40x. But as I increased my magnifications on HJ 1713 from 112x to 167x, I could definitely see that the primary is an F8 yellow-white star, and the secondary is orange. Wow! (I don’t know the spectral class of the secondary).
7. The open star cluster NGC 7160 is about 2˚ from Xi Cephei. I counted 11 stars in and around its boundaries. Most of these stars were white. But I thought one or two of them had an orange tinge. The 2 brightest stars in this cluster are an actual double star. S 800 has magnitudes: A = 7.1. B = 7.9. Sep = 62.7”. PA = 145˚. Both stars are white, and I could effortlessly see them separated at 40x. I pushed my magnifications up to 167x again on the open cluster. NGC 7160 became a wondrous sight, and I whispered “God made all the stars”. So I found that this star cluster has plenty of character. HJ 7160 was first observed by John Herschel in 1829.
8. I know I have reported on Delta Cephei (STFA 58) recently. But it’s a new year – so I thought I would look it again. Magnitudes: A = 4.2. C = 6.1. B is too faint. Sep = 41”. PA = 191˚. Easily split at 11x (in the small apo) and 40x (n the main scope). A is F5 yellow-white. C is B7 blue-white. There was no need to go higher in magnification.
9. And so finally I come to RW Cephei. This variable star didn’t seem as orange as last time. That's probably because of the 10 day old Moon behind me. I observed at 11x and 40x on this cold Monday night. But I was very pleased to see the star with my 70mm apochromatic refractor for the first time at 11x. It’s in a lovely field of stars. There is a 7.3 magnitude star that is called HD 211982 or SAO 34316 (if you prefer) in the same 2˚ fov in the main scope. I thought that RW Cephei had the same magnitude as HD 211982, and I have recorded its magnitude on
www.aavso.org
. As long as RW Cep stays above the 3 storey apartments behind my garden wall I will continue to observe this variable hypergiant star. Its visual magnitude is supposed to vary from 6.0 to 7.6. Its diameter is said to exceed 1000 times greater than our Sun!
That’s the end of my report.
Comments are very welcome.
Clear skies for 2023!
Aubrey.
