16 doubles & 2 triples in Coma Berenices

Hello, all double star admirers.

I was out observing on 2 nights - 9th and 11th May 2020 with my William Optics 158 mm F/7 apochromatic refractor and its accompanying WO 70 mm F/6 small apo which are both supported on a Berlebach Planet alt-az mount. Mirror diagonals are fitted to both scopes. Therefore north is up and east is to the right. Temperatures went down from 17˚ Celsius to 10˚ C on the 1st night. But it turned quite cold on the 2nd night - from 9˚C to 0˚C.

All these doubles and triples are within the boundaries of Coma Berenices. To list them I first check Sissy Haas’ book Double Stars for Small Telescopes and Robert Burnham’s Celestial Handbook Volume 2. After that I go through www.stelledoppie.it to see what other doubles I can have a go at which are near the doubles listed in these 2 books. That website provides magnitudes, separations, some spectral classes and PA’s.

1. I have been noticing that to find 24 Comae Berenices before the sky gets truly dark, I ought to observe the brighter true binary Gamma Virginis (Porrima) first and then move the telescope straight upwards and I will arrive at 24 Comae without any problem. Wow! My WO 70 mm small apo easily splits the latter famous true binary at a mere 11X. In the main scope at 40X, the double is very good indeed. Magnitudes: A = 5.1. B = 6.3. Sep = 20.2”. PA = 272˚. A is slight orange. B is blue okay. The spectral classes are K2 and A3. It is most certainly a good rival to Albireo.

2. 2 Comae, which is northwest of 24 Com, may be an uncertain double but it is very nice. Magnitudes: A = 6.2. B = 7.5. Sep = 3.7”. PA = 236˚. This pair is finely split at 112X. A is yellow-white (F0). B is white.

3. Very close by to 2 Comae is HO 535. It is an optical double. Magnitudes: A = 8.7. B = 11.5. Sep = 3.1”. PA = 141 ˚. To see these 2 stars separated I required 225X. A is a strong yellow-white (F9). B is white. They also looked very good at 280X. HO stands for George Hough (1836 – 1909).

4. I then travelled north up to Stf 1615 which is a true binary. Magnitudes: A = 7. B = 8.6. Sep = 26.8”. PA = 88˚. Easily split at 40X and 112X. A is yellow-white (G5). B is slight blue.

5. HJ 844 is an optical double and is close to and west of Stf 1615. Magnitudes: A = 9.5. B = 11.2. Sep = 12.7”. PA = 352˚. Split at 40X and 112X. A is yellow-white (F9). B is white. HJ stands for John Herschel (1792 – 1871). His father was William Herschel.

6. Very nearby is KU 102. Magnitudes: A = 9.2. B = 11. Sep = 62.7”. PA = 337˚. Split at 40X. Both stars are plain white. This double was most definitely the most bland of the 2 nights. But I was glad to locate it and tick it off. KU stands for Karl Friedrich Kustner (1856 – 1936).

7. Further south we have Stt 245. It is an uncertain double. Magnitudes = 5.7. B = 11.2. Sep = 8.4”. PA = 282˚. Split at 112X and 140X. Both stars are white (A3).

8. I was surprised to discover that 9 Comae is a true binary. It’s just south of Stt 245. Magnitudes: A = 6.4. B = 9. Sep = a massive 545.5”. PA = 224˚. 40X was sufficient to see the colours of the 2 stars. A is yellow-white (F8). B is a pleasant orange. But I have no spectral class on this occasion of B.

9. Stf 1633 is further south and is an uncertain double which I am somewhat surprised that it is the case. Magnitudes: A = 7. B = 7.1. Sep = 8.9”. PA = 245˚. Both stars have the same spectral class of F3 and are yellow-white. Fine tight split at 40X. But a good sight at 112X too.

10. BU 27 is down in the southern part of Coma Berenices and it is a true binary. Magnitudes: A = 7. B = 10.5. Sep = 3.6”. PA = 104˚. 112X is enough to split it, but how good it looked at 140X. A is yellow (G9). B appeared white. BU stands for Sherburne Wesley Burnham (1838 – 1921).

11. HO 53 is very close by and it too is a true binary. Magnitudes: A = 9.2. B = 11.3. Sep = 2.9”. PA = 303˚. A fine split I had at 112X and 140X. A is yellow (G5).

12. Stf 1639 is a triple star and is positioned in the open star cluster Melotte 111. A & B are a true binary, but C is optical. Magnitudes: A = 6.7. B = 7.8. C = 11.4. Sep’s = 1.9” & 91.4”. PA’s = 323˚ & 159˚. This triple is a marvellous sight at 112X up to 167X. That’s because of A & B’s colours. A is white (A7) and B is yellow-white (F4). C is faint and is plain white. A real gem for sure!

13. Triple star 17 Comae is very close by to the east of Stf 1639. A & B are a true binary. C is an uncertain double but what a super colour. All 3 stars are super easy to split 112X. Magnitudes: A = 5.2. B = 6.6. C = 11.6. Sep’s = 146.4” and 324”. PA’s = 251˚ and 269˚. A & B are both white (A0 & A3). But I was utterly amazed to see that C is a beautiful orange star – even though it is so very faint. My Guide 9.1 DVD informed me of that particular idiosyncrasy. Therefore I do recommend 17 Comae to you all.

14. Stf 1643 is a true binary and is placed between 14 and 16 Comae in Melotte 111. Magnitudes: A = 9. B = 9.5. Sep = 2.7”. PA = 3˚. This is definitely a beautiful double to my eyes. Both stars are orange (K2). One directly north of the other. What a super sight it was at 112X and 140X! You can all spoil yourselves with Stf 1643.

15. Stf 1651 is a true binary also in Melotte 111. Magnitudes: A = 8.7. B = 10.1. Sep = 7”. PA = 215˚. Very tight split at 40X. But very good at 112X. A is yellow (G5). B is white.

16. Stf 1652 is a true binary very close to 20 Comae. Magnitudes: A =10.1. B = 10.4. Sep = 6.1”. PA = 178˚. Super tight split at 40X. But very good at 112X. A is yellow (G). B is white. So one star sits above the other. Faint but what a goodie it truly is!

17. Stf 1650 is a true binary right next to 21 Comae. Magnitudes: A = 9.5. B = 10.5. Sep = 10.5”. PA = 178˚. A is yellow-white (F6). B is slight blue (no spectral class).

18. HJL 1069 is my final double and it is a true binary. Its sits above 20 Comae. Magnitudes: A = 7.9. B = 10.1. Sep = 115.4”. PA = 312˚. A is yellow (G7). B is white. Very easy to split at 40X. I went no higher. HJL stands for Jean Louis Halbwachs. I cannot find out whether he’s still with us or did he live in a past age.

There was one uncertain double which refused to split for me on Sunday night 11th May. I knew, before the outset, it was going to be a real test for my refractor. AG 179 has magnitudes 9.9 & 10.6. The separation is a mere 1”. But even up to powers 320X, B would not “pop” out. The position angle is 141˚. I would say those with larger apertures would have a better time splitting it.

Thank you for reading my latest report.

Comments, images and sketches are always welcome.

I don’t appear to have clear skies for tonight Tuesday. But I do feel I ought to have one night’s rest. You see I’ve been observing for the last 5 nights in a row! And I have never had such a thing happen to me before. I should also point out that I’ve had 40 observing sessions so far in 2020 which another record broken!

So clear skies to you all from Aubrey.

Hi Aubrey,

What a great report you've compiled, and the details provided in it are excellent. I very much liked your description of 24 Comae Berenices as a good rival to Albireo. Some say it is the spring-time Albireo!

Big congratulations on splitting HO 535 - it seems like a tricky one - did the 5mm Nagler do the job?

It was great to read about the doubles, and triples you observed in Melotte 111 too. Your description of each object adds so much to what I see when I observe it. In fact, I was out my back garden looking at the cluster myself last night from approximately 22:30 IST. It is a real beauty. I feel it looks gorgeous through the 10 X 50 finder scope.

Believe it or not, I am still struggling to split Porrima. I believe I was on the correct star too! So, I've decided I'm going to sketch what I see when I look through the eyepiece and share it on the forum. By doing so, I'm hoping you, Paul, or anyone else can confirm whether I'm on the right star. In addition to spending time in Melotte 111, I perused the beauties of Bootes: Arcturus, Picot 1; Izar, and that hatchet shaped asterism near Muphrid. I also had look at M3, but I could not resolve any stars though. I then scanned through Corona Borealis. There was a nice grouping of stars, that I'll revisit soon, but the object that stood out for me last night was M13.

Just before midnight, the seeing was so good that I could resolve many stars in the cluster. For some this might sound like no big deal, but this was the first time I managed it from my light polluted back garden. I used different eyepieces, but it look best at 133X. I observed it until 00:18 IST. At that point in time, the clouds blew in, so I called it a night. 

Amazing to think that you've been out five nights in a row. Also, well done on reaching 40 observational session this year - that's hardcore! 

Clear skies,

Darren.



 

 

Yep, Darren.
My 5 mm Nagler sorted out HO 535 this time.
Well done on observing M13 and M3 once again.
I had those clouds too with came in off the Irish Sea at midnight.
Thankfully I had just split the last double at 11.50!
That was HJ 844.
Tonight I am just relaxing and getting ready for tomorrow night.
I have even more doubles at the ready in Coma Berenices.
We're supposed to have clear skies for Wednesday night.
Venus is a real must to start off with.
Then it will be off to Porrima and Coma Berenices.
Please do keep trying Porrima.
There are at least 3 or 4 stars which you could be mistaking for Porrima.

I wish you all the very best,

Aubrey.

Hi Aubrey,

Very many thanks for your reply. I'm going to try and observe Porrima tonight as the sky looks ideal. I'll let you know how I get on. Best of luck with those doubles. 

Chat later, 

Darren. 

Hi Darren.
After I finish with Venus, I will observe Porrima at about 10 pm.
There are no less than 5 other stars which often can be confused with Gamma Virginis.
They are: Rho, Epsilon, Delta, Eta and Beta.
So make sure you see the centre star of the huge "Y" of Virgo with your own eyes before you use your scope.

All the very best,

Aubrey.