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Some doubles and triples in Aquila

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#1 flt158



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Posted 13 August 2019 - 08:44 AM

Hello everyone. 

I just thought I ought to encourage those who are interested to hunt for a few doubles and triples near Epsilon Aquilae. 

Epsilon Aquilae is a magnitude 4 star which I cannot quite see with my unaided eye in the north western part of Aquila.

I live in a Bortle 9 area in South Dublin, Ireland.  

But Zeta Aquilae, which is in very close proximity, is visible with my own eyes. It is of magnitude 3.


So on Monday night 12th August 2019, I printed off a finder chart for the entire area including the lovely open star cluster NGC 6709. 

But even before I did that I had a quick look in Sissy Haas' very famous book Double Stars for Small Telescopes. 

I noticed there is a good listing of double stars in Aquila in that book.

I used www.stelledoppie.it for all magnitudes, separations and PA's and colours.  


My telescope is a William Optics 158 mm apochromatic refractor f/7 placed on a Berlebach Planet alt-az mount with mirror diagonals.  


1. Epsilon Aquilae is an optical triple star with magnitudes 4, 10.6 and 11.3. 

The separations are 123.4" and 145". The PA's are 185 and 160 degrees. 

The primary is decent orange; but the 2 optical companions are so faint they looked simply white. 

Because of the wide separations I did not find it a very interesting triple star -although the orange tint of the primary was nice to behold.

112X was all I required to see A, B and C with plenty of space between.  


2. 11 arc minutes south of the above star we have a much more interesting triple. 

The designation is Stf 2428.

All 3 components were clearly seen at 112X, 140X and 167X. 

The magnitudes are 8.2, 10.3 and 11.1. 

I have to say that the primary is yellow white alright. But the C component has a truly remarkable orange -red hue. 

To greatly appreciate it I used powers up to 280X! It is a true gem in every sense. Please do check it out. 

I promise you will be most impressed. 


3. Almost directly north of of Epsilon Aquilae, there is a true binary with the strange designation AG 368 which is effortlessly easy to split. 

Even though it is a bit fainter than the planet Neptune, there is no problem seeing A and B split at 40X. The primary is very slightly orange. 

The magnitudes are 9.3 and 10.3. Separation is 17.3". PA is 317 degrees. 

I also used 112X on it. 


4. I have observed the open star cluster NGC 6709 a number of times in the past.  

It is 6 degrees south - south west of Epsilon Aquilae. 

And it is a splendid cluster for sure. 

I must see nearly 80 members at 112X. 

Its overall magnitude is 6.7 and is 13 arc minutes in diameter quite rich and a little bit compressed. 

What I did not know was that there are 2 fine doubles inside its boundaries. 

I could only see the A and C components of HJ 270. B is too faint. 

The magnitudes are 9.8 and 9.2. Separation: 65.8". PA: 248 degrees.

BU 1464 is right next to it. Its magnitudes are 9.2 and 9.7. Separation: 22". PA: 23 degrees.

These 2 doubles brought great pleasure to me at 112X within the whole open cluster NGC 6709. 


5. STTA 174 is very easy to see its 2 stars at 40X northwest of NGC 6709. 

The magnitudes are 7.5 and 8.3. Separation is 104.6". PA is 158 degrees. 

The primary has a slightly blue tint. 


6. Finally I finish with a stunning double: Stf 2404. It is very near STTA 174. 

At 112X I find its colours are completely captivating. 

Both are good orange in my apo. 

The spectral classes are K5 and K3. 

The magnitudes are 6.9 and 7.8. PA: 182 degrees. That's straight down for my refractor. 

The stars are easily split at 112X. But higher magnifications are very welcome to this pair. 

I went up to 280X!

It is listed in Sissy Haas' book. 

None of the others are -but that's okay. 

www.stelledoppie.it regularly comes up with the goods. 


That's it for now. 

Contributions are always welcome. 


I wish you all clear skies and happy hunting for these fascinating systems in Aquila. 


Aubrey (Flt 158).  

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#2 ssmith


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Posted 13 August 2019 - 10:12 AM

Hi Aubrey -
Great report !  I have visited several on your list but have added a couple of them to my to-do list.
Here is an additional one in Aquila to try which I checked out just a couple of nights ago - 5 Aquilae.
It is listed as a triple but only AB is truly physical.  I could not see the 11.3 mag "C" component (using my 120mm scope) as the nearly full moon was only a short distance away.  Haas also noted that she was unable to detect the "C" component.  "C"  is distinctly red-orange in my photos but I am unable to find any spectral data on this star.  
Sky Safari seems to have some bogus data on this one and when I first observed this and looked at the Sky Safari plot I wasn't even sure I was in the right location (see screen shot).
5 Aql STF2379 120mm 8-11-19 3f.jpg
5 Aql.jpg

Edited by ssmith, 13 August 2019 - 12:03 PM.

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#3 ssmith


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Posted 13 August 2019 - 01:50 PM

Aubrey - 


Here is a stacked photo of NGC 6709.  I've had the subs sitting in my files for several years but never got around to processing them until now.


It's understandable that you didn't see the B component of HJ 870 shining at magnitude 12.0.


The components of SMA 82 will also be visually unreachable for many of us.



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#4 flt158



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Posted 13 August 2019 - 02:58 PM

As ever, Steve, it is brilliant to hear from you!


Your images are very dramatic as always!


You have me busily searching in my diaries going back to the year 2000 to see when I did observe 5 Aquilae. 

But it clearly is the case it has been a very long time since I last observed it. 

(Probably back in the 1980's or the 1990's)

Those ancient diaries are up in my attic -would you believe?

Therefore it is high time to observe it again. 

I will try and see component C also this time. 

Its position is on Guide 9.1 DVD alright. 

It is just that I was nowhere near 5 Aquilae last Monday night. 

And I will seek out other doubles in this crammed area around NGC 6709. 

I'll add them in here on this post. 

Our next few nights are going to be very overcast. 


But what a beauty that fine double Stf 2404 is. 


By the way, I did purchase a brand new 2 speed Crayford focuser for my William Optics apo. 

And it is gloriously butter smooth -especially the fine focus. 

It was expensive, but to me it was very much worth every cent. 


Clear skies eventually, 



#5 rugby


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Posted 13 August 2019 - 05:36 PM

Aubrey:  What altaz mount are you using?

#6 flt158



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Posted 14 August 2019 - 02:32 PM

Thank you for your question, Rugby. 

It is the very mount I purchased when I got my William Optics 158 mm apochromatic refractor. 

A Berlebach Planet altazimuth mount. 

Above it I have a DM6 telescope head that the refractor sits on. 

I have no counterweights fitted at all. 

There is most certainly no way I am very going to change this perfect system. 

It is that good!!


Also I must thank you, Rugby, for informing us all of that very fine triple star Stf 2428 a week or two back. 

Finding it helped me "discover" the other doubles nearby -the one listed above. 


Kindest regards from Aubrey. 

Edited by flt158, 14 August 2019 - 02:33 PM.

#7 rugby


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Posted 18 August 2019 - 08:28 PM

Flt158:  Indeed  the dm6 on a Berlebach planet would be a wonderful combination when used with a 158 apo. Do you have goto capabilities?. My situation is a lightweight version of your setup. I have a 120 apo on a castor 2 head which sits on an old meade tripod.  It works but anything heavier would be a disaster..  Please post a pic if you have time.

#8 flt158



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Posted 29 August 2019 - 03:04 PM

Hello, everyone, once again. 


On Monday 26th August I was out again with my William Optics 158 mm f/7 apochromatic refractor under Bortle 9 skies in my back garden. 

There was no wind or turbulence throughout the whole night for 3.5 solid hours. 


I had printed off a good map from my Guide 9.1 DVD. 

The first 6 doubles are all north of the open star cluster NGC 6709 in Aquila. 

It is my first time I have ever observed any of them. 


1. Stta 174. A= 7.5. B= 8.3. The separation is very wide at 104.6". PA is 158 degrees. Easily split at 40X of course. 

It is an optical double. 


2. Stf 2396. A= 8.1. B= 11.3. Separation: 82". PA= 337 degrees. Because that secondary is extremely faint, I required 112X to see it. Optical double. 


3. Stt 362. A= 8.3. B= 11.9. Sep: 7.8". Quite a tough to see both stars. 167X was sufficient to see A and B with a decent amount of black space between them. Astronomers tell us they are uncertain if it is a true binary. But that's okay. 


4. Stf 2402. We all love tight doubles. Here is one for you all. A= 8.9. B= 9.3. Sep: 1.4". PA= 208 degrees. It was not fully split at 112X. But at 140X and 167X, my scope split it alright. Gorgeous sight! -even though it is uncertain if it's a true binary. Never mind -what a grand but faint double. It is northwest of NGC 6709. 


5. Stf 2408. A= 8.5. B= 9.4. Sep= 2.3". PA= 91 degrees. Super tight split at 112X. Uncertain double -but it definitely is worth seeking out. 


6. BU 265. A= 7.4. B= 9.2. Sep= 1.4". PA= 231 degrees. So you want a real challenge. A full 1.8 magnitude difference in delta mag plus it is so tight. 167X was not enough. But I am very happy to say my 225X 5 mm Nagler saved the day (or night). A is white. B is yellow. What an achievement to an uncertain double!


7. 23 Aquilae. A=5.3. B= 8.3. Sep= 3.2". PA= 2 degrees. I read about this tough true double over on the sketches forum on Cloudy Nights. It has been about 10 years since I observed 23 Aql. My apochromatic refractor nearly had it split at 112X, and that is considering there is a full 3 magnitude difference. Sitting on top of the yellow primary was the faint secondary. At 140X I got the desired split. But I did increase up to 167X and 225X. It brought great pleasure to the eye. 


8. And so we come to Steve Smith's challenge. Can I see all 3 components of 5 Aquilae? And at what power? The magnitudes are: A= 5.9. B= 7.0. C= 11.3. The separations are 12.6" and 21.8" with PA's of 122 and 156 degrees. Thankfully because of those decent separations I could see A and B split at 40X very easily. The C star was no problem either -seen at 112X and 140X. I increased my magnifications up to 167X and 225X to further prove to myself that all 3 stars were visible at all times. 


It was one of my best observation nights of 2019. 


Please see my original report of other exciting doubles and triples.  


Comments are very welcome. 


Clear skies, 



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#9 payner


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Posted 29 August 2019 - 04:37 PM

You had some fine targets selected, Aubrey, and your enjoyment came through in your report. Thanks for sharing and I'm going to check in on some of these.




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#10 MP173


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Posted 03 September 2019 - 11:16 AM

I stumbled onto 5 Aquilla on August 28th and checked the data on STelle Doppie noting it is a triple.


I returned last night and did in fact pickup the 11.3 C star.  It was almost due south of the B.  Steve, your photo confirms what I saw.


The C was observed with AT102ED and 9mm Plossl at 78x.  Seeing was not very good but this surprisingly was viewed.  Made my night.



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