Some doubles and triples in Aquila

3 months 3 days ago #107767 by flt158
Some doubles and triples in Aquila was created by flt158
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.
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 in 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.
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3 months 3 days ago #107768 by scfahy
Replied by scfahy on topic Some doubles and triples in Aquila
Thanks again for an excellent report on your observations.
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3 months 3 days ago #107769 by Until_then-Goodnight!
Replied by Until_then-Goodnight! on topic Some doubles and triples in Aquila
Hi Aubrey, 

Very many thanks for your detailed description of these doubles and triples in Aquila. I must attempt to give some of these a go during the next clear night. Also, those references (book and website) seem worth following-up on too! 

Kindest regards, 

Darren. 
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2 months 4 weeks ago #107770 by Fermidox
Replied by Fermidox on topic Some doubles and triples in Aquila
Interesting you cannot see Epsilon Aquilae with the naked eye Aubrey; I can get down to mag 5.9 in rural Limerick and have seen Uranus without optical aid. On the other hand, clear nights have been very rare down here this Summer, so to give us that doubles report I think you must still be in Argentina :D

All the best,
Finbarr.
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2 months 4 weeks ago #107771 by flt158
Replied by flt158 on topic Some doubles and triples in Aquila
You would think I would see a magnitude 4 star with my eyes, Finbarr.

And, gosh, I would be thrilled to see Uranus the same way.

If only I was still in Argentina -if only!

Still thank you for your contributions, Finbarr.

Maybe we will have one or two clear nights very soon.

Kind regards,

Aubrey.
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2 months 3 weeks ago #107772 by johnomahony
Replied by johnomahony on topic Some doubles and triples in Aquila
Glad the new focuser is working out well. Great observing report. Looking forward to trying out my new 4" WO refractor.

The Lord giveth, the Revenue taketh away. (John 1:16)

www.flickr.com/photos/7703127@N07/
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2 months 3 weeks ago #107773 by flt158
Replied by flt158 on topic Some doubles and triples in Aquila
..... whenever we get some clear skies, John.

I wonder when are we going to have some clear skies.
There is so much high and medium hazy cloud over us constantly.
But that's a typical August.

By the way, I hope your focuser is equally as good as mine!
A 4" refractor is lovely and light to handle.

Kind regards from Aubrey.
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2 months 2 weeks ago - 2 months 2 weeks ago #107787 by flt158
Replied by flt158 on topic Some doubles and triples in Aquila
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 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. 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.

Comments are very welcome.

Clear skies,

Aubrey.
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2 months 2 weeks ago #107790 by Fermidox
Replied by Fermidox on topic Some doubles and triples in Aquila
Very impressive that you can split those tight and faint doubles in Bortle 9 skies Aubrey. Just shows what can be achieved with a good scope in unfavourable conditions, and that light pollution need not necessarily be a barrier to productive observing.

Finbarr.
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2 months 2 weeks ago #107791 by flt158
Replied by flt158 on topic Some doubles and triples in Aquila
Thank you for your kind comments, Finbarr.
All we need is a bit of patience and to stick with the desire to split even the tightest doubles.
Sometimes we will need that extra magnification to see the very faint.

What fun is to be had. NGC 6709 is a wondrous open cluster. It led be to many hidden binaries.
That double Stf 2404 has great charm. Easily wins me over.

Kind regards to all,

Aubrey.
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