Observations - 17/01/23

On Tuesday night 17th January 2023 I set up my William Optics f/7 158mm and my WO f/6 70mm apochromatic refractors in my back garden. Sunset occurred at 16.39UT. Both scopes are always placed on my Berlebach Planet altazimuth mount. I observed from 16.15UT until 19.30UT. So it was a quite a long marathon. The 22 km/h winds kept any dew at bay. I was even shivering quite a lot at the end of this observing session because of that wind - despite wearing plenty of very warm clothing. The air temperature was 1˚ to 0˚ Celsius. Top priority was observing some double star systems in Cepheus.  
But before all that I observed the -2.3 magnitude Jupiter for about 30 minutes. The Earth is moving away from the largest planet all the time. Its distance from us was over 787,500,000 kms. Its angular diameter was 37.5”. On the eastern side of the largest planet were 3 of its moons. Furthest out was Callisto. In the middle was Europa. Then Io was closest to Jupiter. I must say these 3 moons formed a very nice and gentle curve. On the western side of Jupiter was lonely Ganymede. However at 167x I observed another curve in the North Equatorial Belt. It was a “double” dark curve which looked like a double version of the symbol we sometimes use for the word “approximate”: ~. I have contacted an imager on www.cloudynights.com who saw the same dramatic feature a while ago. I don’t remember observing such a disturbance in the clouds of Jupiter ever before. I thought at first it was a multiple festoon. But no - it wasn’t. I have since encouraged imagers on Cloudy Nights to keep an eye on Jupiter. The planet can conjure up some nice surprises for time to time. 

All these double star systems in Cepheus can be checked out on www.stelledoppie.it  
As I have mirror diagonals fitted my North is to the left and my East is up. This takes some getting used for checking out the PA’s of the secondary stars.

1. Beta Cephei (Alfirk) came first once again. Magnitudes: A = 3.2. B = 8.6. Sep = 13.5”. PA = 251˚.  As the sky was still bright, and although that had already occurred an hour earlier, I found the primary to be white. But the secondary was definitely blue-white. Separated at 40x and 112x. It’s also known as STF 2806. In Burnham’s Celestial Handbook it is described as a relfix double. 

2. The true binary Xi Cephei (Alkurhah) came next. Magnitudes: A = 4.5. B = 6.4. Sep = 8.1”. PA = 274˚. No problems separating it again at 40x and 112x. The primary was white. The secondary was blue-white as before. Very nice teardrop effect.  

3. I am finding the nearby true binary HJ 1713 quite irresistible. Magnitudes: A = 8.7. B = 10.7. Sep = 18.7”. PA = 125˚. No hassle seeing A and B split at 40x. But at 112x I notice that the primary is white and the secondary is orange. Delightful!

4. HJ 1739 is a true binary – but it’s difficult. Magnitudes: A = 9.3. B = 11.2. Sep = 19”. PA = 63˚. Thankfully my sky was dark at this stage. But the secondary just would not appear until 225x. Even then it was seriously faint. 280x gave a much better view of this toughie. 

5. STT 457 is a relfix double according to Burnham’s Celestial Handbook. And it is also very difficult to split - no doubt because of its delta magnitude. A = 6. B = 8.2. Sep = 1.4”. PA = 246˚. I knew I was going to have my work cut out with this double.  At 280x that nasty secondary just wouldn’t “pop” out. I had to use my Nagler 3.5mm eyepiece. It yields 320x when slotted into my 158mm refractor. I could see the secondary alright – and the most tender of black gaps. I didn’t find the view particularly stunning; but it was a privilege nonetheless.

6. STF 2844 is an uncertain double; but it’s nice all the same. Magnitudes: A = 7. B = 10. Sep = 11.9”. PA = 260˚. Nice split at 40x. At 112x the primary was a nice K0 orange. The secondary was white. 

7. STF 2843 was the “star” of the night. A & B are a true binary. But C is optical. Magnitudes: A = 7. B = 7.3. C = 11. Sep’s = 1.4” & 54.7”. PA’s = 155˚ & 277˚. Therefore this system is a triple star. A & C were seen at 112x. But the true double was trying to split at 140x and 167x. However at 225x success was had. The tiniest black gap appeared eventually with my Nagler 5mm. What a magnificent sight it was to behold! 

8. An easy double next. In fact, binocular users will easily separate ARG 43 at minimal powers. It may be an uncertain double – with magnitudes: A = 6.4. B = 6.8. Sep = 100.4”. PA = 128˚. 11x is my lowest power – and ARG 43 was easy to see cleanly separated. But this double has a trick up its sleeve: its colours! Rather than an orange and blue double, like Albireo, Izar and a host of others, it’s the other way around. I believe my Heavenly Father has a sense of humour. The primary is B3 blue and the secondary is K5 – quite a rich orange. I noticed these colours at 112x. For sure – K5 stars are delightful. Check it out if you wish to.   

9. STF 2836 and WAL 140 form a triple star. Magnitudes: A = 6.5. B = 10.4. C = 10.5. Sep’s = 11.8” & 64.5”. PA’s = 155˚ & 253˚. The A & C stars have the designation of WAL 140. This double is an uncertain double with magnitudes: A = 6.5. C = 10.5, and were easily separated at 40x by yours truly. STF 2836 is a relfix double. Magnitudes: A = 6.5 (again). B = 10.4. The primary is F4 yellow-white. The other 2 fainter stars are white. I observed all 3 stars separated at 112x. A nice view. WAL stands for the Swedish astronomer Ake Wallenquist (1904-1994). 
 
10. HJ 1711 is an optical double. Magnitudes: A = 8.2. B = 10.9. Sep = 8.8”. PA = 255˚. Good separation at 112x. The stars are F5 yellow-white and white. 

11. Finally I observed the true binary STF 2853. Magnitudes: 8.1. B = 10.2. Sep = 3.2”. PA = 188˚. I got a good tight separation at 140x and 167x this time. The primary is F5 yellow-white. B is white.     

Thank you for reading my latest report. 
Comments, corrections and images are very welcome. 
I wish you all clear skies, 
Aubrey.      

Hello folks again. 

These were the 4 other doubles I attempted on Thursday night 19th January 2023 with my refractor. 

1. The first one proved very easy. STTA 226 is a true binary. Magnitudes: A = 7.5. B = 8.9. Sep = 76.3". PA = 245 degrees. I had no hassle seeing both stars separated at 40x. At 112x I could see that the primary was G8 yellow. The secondary was white. STTA stands for Otto Struve Supplement. 

2. Next up was the first of my challenging doubles. STF 2823 is an uncertain double. Magnitudes: A = 9.2. B = 10.1. Sep = 1.5". PA = 254 degrees. I had the feeling this double was going to be very difficult before I set out to give it a go. How right I was! I had no sign of the secondary at 225x and 280x. Once again I reached for my Nagler 3.5mm which yields 320x, and once again it did the business! My seeing conditions must have been remarkably good. Plus I had no Moon either, and that always helps. The separation was enough to see that tiny speck of a star hanging almost directly downwards from the primary. Even though both stars are white and so faint, it brought great joy to my heart to see this seriously tight double. Larger apertures could give STF 2823 a go. It was first observed in 1832 by F. G. W. Struve. Also I find it very strange that Stelle Doppie considers this double as an uncertain. They are so tight after all. Could they not be a relfix double - i.e, the 2 stars are travelling together through space?

3. HU 938 is another uncertain double. Magnitudes: A = 8.8. B = 9.9. Sep = 1.3". PA = 147 degrees. This double just would not split at all. I dug out my 3mm 374x Radian and the secondary would not show up. I'm certain that the combination of its tightness plus the delta magnitude of 1.1 was sufficient for me to be blind sighted. Never mind! It was worth the try. 

4. STF 2835 is an uncertain double. Or could it not be a relfix double? Magnitudes: A = 9. B = 9.9. Sep = 1.9". PA = 272 degrees. The primary is F2 and yellow-white alright. The secondary is white. That 0.9 of a delta magnitude is enough to cause some difficulty on splitting this double. But I got it alright - and with that same 320x eyepiece as before. This time the secondary "hung" straight down from the primary. It's another teardrop effect- similar but far fainter than Xi Cephei. 

5. Darren gave me the heads up on this last double. Thank you, Darren! The planet Mars is currently very close to the true binary 62 Tauri (STF 534). The binary's magnitudes are: A = 6.4. B = 7.9. Sep = 29.1". PA = 291 degrees. Some of you with small telescopes might try and observe this nice conjunction. I had no problems seeing the yellow-orange planet and the double split at 40x on this Thursday night in the same field of view. There is even another bright field star in between both celestial objects. . 

Have fun!

Clear skies from Aubrey.  

Hello Aubrey,

I know we've chattered over the phone about some of these observations, but reading them always makes me feel I'm looking through the eyepiece - your detailed descriptions are excellent! 

I particularly enjoyed reading about your observations on Jupiter, and that interesting feature - the one that resembled the approximate symbol - must have great to see.

Going through the double stars you observed,the term 'relfix' is one I've not heard before... What does it it mean?

Clear skies for now, and I'm sorry I couldn't get to read and reply to your reports before now, but the past two weeks were particularly hectic.

All the best,

Darren. 

 

Excellent to hear from you again, Darren, and from anyone else here on my favourite astronomy website!. 

I'm admiring that word "chattering". 
It has been many years since I heard it. 

Yes. Well - "relfix" simply means the 2 stars are travelling through space together, 
They are not orbiting one another at all. 
They are like 2 cars travelling side by side on a dual carriageway. 
One star is probably travelling faster that the other. 
So the separation will increase or decrease over time. 

Clear skies from Aubrey.  

Hi Aubrey,

Very many thanks for clarifying what the term 'relfix' means - that's much appreciated!

Clear skies,

Darren.