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.
  