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Five Close Friends in Cygnus

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#1 nerich

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Posted 27 June 2020 - 03:51 PM

Hello All, 

Is there a more wonderful part of the sky for double star enthusiasts than Cygnus? There's so much to see here that I get overwhelmed planning my observing sessions. I have to calm down and remind myself that I can't observe everything on any single night. 

Case in point is this magical two-and-a-half-degree strip of sky centered around 19 hours and 45 minutes and running between 33° and 36° north (or more simply put, just a couple degrees west of Eta Cygni). Here you'll find a showpiece or two, as well as a couple of subtler delights. 

Moving north to south, I'll start with STF 2578 (6.4/7, 14.9"). At low power I noticed a slight color contrast. The spectra are actually quite close, B9 for the primary and A0 for the secondary; but strangely, I saw the secondary as bluer in tone, flirting with green and grey as the power went up. To the west/southwest is a third companion, which I believe is the magnitude 9.2 F component. At 72x (2.1mm exit pupil in my 150mm Mak), I caught a glimpse of something curious off to the north: a very dim double star, forming the southeastern vertex of a right triangle of similarly dim stars. At this power it was clearly double but not well resolved with direct vision. 

Bumping the power to 90x (1.7mm exit pupil) helped a little. I could estimate the PA as either south/southwest or north/northeast, though I wasn't sure which star was the brighter of the two. 120x (1.25mm exit pupil) resolved the pair fully and revealed that the southern star was slightly brighter, making the PA north/northeast. 

A little searching this morning gave a label to my mysterious and shy new acquaintance: this is ALI 161 (10.8/11.2, 8.5"), discovered by Dr. Akbar Ali. What a joy to learn about this gentleman! Dr. Ali was director of Nizamiah Observatory in Hyderabad, India, from 1944 until his death in 1960. There he participated in the Carte du Ciel project, procured a 48" reflector (unfortunately not completed during his lifetime), and mentored famed Indian astronomer Vainu Bappu, whose father was also an astronomer at Nizamiah. Unfortunately, Nizamiah Observatory presently stands unused, as excessive light pollution has made scientific work there difficult. I'm grateful to have caught a glimpse of this modest double and to learn a little of its discoverer. 

Moving south I came to H V 137 (6.2/8.2, 39"). Some of you know what a huge fan I am of Omicron Dra, and this pair bears an uncanny resemblance: a G-type primary, a color-shifting secondary, and a very similar separation. Increasing the power brought B's difficult hue firmly into blue territory, contrasting beautifully with brilliant brass-colored A. The Admiral calls this a "fine object," and gives the colors as straw and smalt blue. I'll take it! 

(note: searching Stelle Doppie for these Herschel designations can be a frustrating experience, no matter how you style them; for those of you interested in looking this one up, the WDS number is 19459+3501). 

Further south still brings us to a pair of pairs, 17 Cygni (5.1/9.3, 26") and STF 2576 (8.5/8.6, 3.1"). The relationship isn't purely visual: WDS actually lists STF 2576 as the F and G components of the larger 17 Cygni system, and notes a common proper motion between the pairs. Before being merged into the 17 Cygni file in WDS, the AF pair was cataloged as LEP 93, one of the CPM pairs of Sebastien Lepine. 

Visually, this group is a stunning sight. 17 Cygni A is a bright sandy color, and B a strong orange despite its relative dimness. Nearby to the southeast is the 9.4 C component, nearly as bright as B but much lighter in hue. To the south is a row of three stars, gently curving from northwest to south. 

STF 2576 is a perfect miniature of a double, split cleanly even at 45x. Raising the power to 72x and then 90x brought out a pinkish brown color in both stars, befitting their K spectral type. 

Below is my sketch of the whole scene:



17Cyg.png





And again, with an inset to show the detail on STF 2576: 



17CygInset.png





That's all for now! Comments and corrections most welcome. 


 


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#2 rugby

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Posted 27 June 2020 - 09:03 PM

well done nerich


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#3 flt158

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Posted 28 June 2020 - 07:25 AM

Hi Nick. 

 

Thank you for giving us another super report!

Cygnus is indeed a magnificent constellation of all sorts of reasons. 

Your sketches are extremely good too. 

Your descriptions of the colours are most excellent as ever. 

 

I have split 17 Cygni as some stage. 

But not STF 2576. 

 

I have much observing to do in The Swan. 

Although I have enjoyed splitting quite a few other doubles and triples in other parts of the constellation.  

 

Please keep up the good work, Nick. 

 

P.S. Roll on the World Snooker Championship!

Stephen Maguire won the recent tournament in Milton Keynes in London in a thrilling final. 

 

Best regards from Aubrey.  


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#4 nerich

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Posted 28 June 2020 - 10:26 AM

Hi Nick. 

 

Thank you for giving us another super report!

Cygnus is indeed a magnificent constellation of all sorts of reasons. 

Your sketches are extremely good too. 

Your descriptions of the colours are most excellent as ever. 

 

I have split 17 Cygni as some stage. 

But not STF 2576. 

 

I have much observing to do in The Swan. 

Although I have enjoyed splitting quite a few other doubles and triples in other parts of the constellation.  

 

Please keep up the good work, Nick. 

 

P.S. Roll on the World Snooker Championship!

Stephen Maguire won the recent tournament in Milton Keynes in London in a thrilling final. 

 

Best regards from Aubrey.  


Thanks so much Aubrey! I know you've still got some work left in Corona Borealis, but when you finally make your way to Cygnus I look forward to hearing your opinion of the magnificent STF 2576. The color was enchanting. 

And how about that Maguire! First reserve, no less. I'm hoping that another illustrious Scotsman, a certain Mr. Higgins, makes it to the WSC final for a fourth year running. What a relentless show he always puts on! 


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#5 MP173

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Posted 28 June 2020 - 09:44 PM

Nick:

Great report.  So much to view in Cygnus.  I spent about 6 sessions last July exploring the region, not only doubles but also open clusters and just roaming around the cross area.

 

Next time from eta head east and north...lots to view.

 

Complete agreement regarding searching the Herchels in S.D.  Difficult to search.

 

Ed


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#6 nerich

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Posted 28 June 2020 - 10:29 PM

Nick:

Great report.  So much to view in Cygnus.  I spent about 6 sessions last July exploring the region, not only doubles but also open clusters and just roaming around the cross area.

 

Next time from eta head east and north...lots to view.

 

Complete agreement regarding searching the Herchels in S.D.  Difficult to search.

 

Ed


Thanks Ed! Yeah, I've been trying to divide my time in Cygnus between doubles and open clusters. There are too many good ones to pass up! Definitely due for some more roaming in Cygnus before the summer is out.

Thanks again for the compliments.  


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#7 rugby

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Posted 30 June 2020 - 10:06 AM

Nick: I followed your star tale in Cygnus and have to agree it is a stunning area to observe. The curving line of three stars South of 17 dominates the field and leads the eye to another gorgeous area around S726. So here you have four pairs lined up North-South each with a distinct personality to attract the eye.
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#8 Forward Scatter

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Posted 30 June 2020 - 10:23 AM

Cygnus rocks in so many ways!


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#9 nerich

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Posted 30 June 2020 - 10:31 AM

Nick: I followed your star tale in Cygnus and have to agree it is a stunning area to observe. The curving line of three stars South of 17 dominates the field and leads the eye to another gorgeous area around S726. So here you have four pairs lined up North-South each with a distinct personality to attract the eye.

Well dang, now I have to go back and find S 726! With a K-type primary, it looks like a real charmer. Thanks for alerting me to this one!


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#10 rugby

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Posted 30 June 2020 - 12:25 PM

It is the cascade of small stars south of S726 that stands out. Moonlight will lessen the impact.
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#11 Rich5567

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Posted 01 July 2020 - 03:42 PM

Thanks so much Aubrey! I know you've still got some work left in Corona Borealis, but when you finally make your way to Cygnus I look forward to hearing your opinion of the magnificent STF 2576. The color was enchanting. 

And how about that Maguire! First reserve, no less. I'm hoping that another illustrious Scotsman, a certain Mr. Higgins, makes it to the WSC final for a fourth year running. What a relentless show he always puts on! 

Ahhhh, you two are snooker fans like me.

 

I'm backing Maguire for the upcoming world championship, can't wait. The senior championships came to my area in October and I saw Willie Thorne, John Virgo, Jimmy White etc, great day. Sat right at the front too, great view.

 

 

They is almost too much to much to see in Cygnus, I have barely dipped into this constellation for some reason, as soon as the night returns I shall do a session in the swan.

 

 

Rich.


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#12 nerich

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Posted 01 July 2020 - 04:06 PM

Ahhhh, you two are snooker fans like me.

 

I'm backing Maguire for the upcoming world championship, can't wait. The senior championships came to my area in October and I saw Willie Thorne, John Virgo, Jimmy White etc, great day. Sat right at the front too, great view.

 

 

They is almost too much to much to see in Cygnus, I have barely dipped into this constellation for some reason, as soon as the night returns I shall do a session in the swan.

 

 

Rich.


I am green with envy, Rich! But with Virgo at the table instead of in the booth, who was there to wonder out loud where the cue ball was going? lol.gif 

Anyway, sorry for going off-topic. Yes, much more to see in Cygnus and in the surrounding environs, Vulpecula included. Speaking of which, it's that time of year again for those of us with 6 inch scopes. Another shot at 16 Vul is in order! 

Aubrey, if you're still reading, remind me: have you split 16 Vul? 
 


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#13 flt158

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Posted 01 July 2020 - 04:18 PM

Hi Rich. 

I very much adore Mu Cygni as a true binary. 

I see on www.stelledoppie.it that it is narrowing as each year goes by. 

The A star is NOT visible to me with my own eyes. Its magnitude is +4.75. 

 

Right now on the east coast of Ireland the rain is pelting down. 

We have had 1 full week of 100% overcast skies each and every night. 

And the upcoming 2 or 3 nights are still staying that way. 

It is a typical Irish summer - I'm afraid. 

 

By the way, wouldn't it be good to discuss the World Snooker Championship on a different forum?

Can anyone suggest that?

I could talk snooker for hours. 

I have written records going back to 1986 of the WST. 

I also should admit I fell in love with the sport when we first received BBC 2 in the early 1970's. 

The programme was Pot Black. 

And I fell in love with the sport on a black and white television. 

I kid you not!!

Anyway - that's enough from me. 

I do hope the skies are more clearer wherever you are, admirers of double stars.  

 

Best regards from Aubrey. 


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#14 flt158

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Posted 01 July 2020 - 04:33 PM

I am green with envy, Rich! But with Virgo at the table instead of in the booth, who was there to wonder out loud where the cue ball was going? lol.gif 

Anyway, sorry for going off-topic. Yes, much more to see in Cygnus and in the surrounding environs, Vulpecula included. Speaking of which, it's that time of year again for those of us with 6 inch scopes. Another shot at 16 Vul is in order! 

Aubrey, if you're still reading, remind me: have you split 16 Vul? 
 

Much to my amazement, Nick, I have only observed 3 celestial objects in Vulpecula. 

1. M27. 

2. 6-8 Vul. This optical double is highlighted in Sissy Haas. 

3. STF 2521 which is a quadruple star. 

4. BD Vul which is a carbon star. 

5. Collinder 399 the Coathanger.  

6. NGC 6800 open cluster. 

7. NGC 6830 open cluster. 

8. NGC 6793 open cluster. 

 

So sorry, Nick. But no I haven't had a go at 16 Vul. 

I have just checked with Stelle Doppie that its separation is stagnant at 0.849" over the next few years. 

But its PA is very slowly increasing. 

So I ought to give it a go during September. 

In the meantime, I'm still awaiting one clear night to finish off Corona Borealis. 

Then a re-visit to Lyra is highly advised.  

 

Clear skies to all, 

 

Aubrey. 


Edited by flt158, 01 July 2020 - 04:33 PM.

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#15 rugby

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Posted 01 July 2020 - 04:59 PM

TO Aubrey, Nick et al: played a lot of snooker in my yoot(youth). Boy was I bad!. I have a close double star sideline going on between responding to mailings. It involves a lot of STT pairs which seem to have the closeness and brightness I need to push my optics. 16 Vulp is one of the pairs I found last summer. Will be nice to see it again. Aubrey I wish you clear skies. i am on the 5th night in row of cloudless nights.
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#16 flt158

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Posted 01 July 2020 - 05:41 PM

Hi Rugby. 

That's brilliant cool word: Yoot!

I like it. 

I'm terrible too playing snooker. 

Love to watch the experts playing it though. 

 

Did you actually split 16 Vulpeculae successfully?

And if so, what magnification did you use?

I am very pleased you are getting clear skies at present, Rugby. 

I hope my turn will come some time soon. 

 

Best regards from Aubrey. 


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#17 ssmith

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Posted 02 July 2020 - 08:39 AM

Here is a wide field photo taken seven years ago through my C80ED scope of 17 Cygni and the surrounding area which shows the numerous double stars in the immediate area. 

 

A high-res version of the photo can be found Here.

Attached Thumbnails

  • 17 Cygni & Environs 9-23-13 80mm 004 rev1 small.jpg

Edited by ssmith, 02 July 2020 - 08:44 AM.

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#18 payner

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Posted 02 July 2020 - 09:48 AM

Great pic, Steve and amazing field of multiple stars.


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#19 nerich

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Posted 02 July 2020 - 09:53 AM

Nice work Steve! 



#20 The Ardent

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Posted 02 July 2020 - 09:56 AM

Next time in Cygnus check out Espin 2297.
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#21 nerich

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Posted 02 July 2020 - 10:06 AM

Next time in Cygnus check out Espin 2297.

Looks like a heck of a system! I should be able to grab at least a few of those 17 components. 


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#22 river-z

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Posted 03 July 2020 - 03:56 AM

I read this report last week and added a few pairs to my list of doubles to check out once clear skies returned to the southland.  Tonight was the night and featured 10 doubles before I came in.  I checked out a couple stars in Cygnus.

 

S 726 is indeed a beautiful pair.  To my eyes, a bright yellow primary star with a bluish secondary.

 

Mu Cygnus looked like a peanut.  I went up to 500x but couldn't split it.  I think the fact that it's pretty low in the sky makes it a bit tougher right now.  I'll have to try again later in the summer.


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#23 flt158

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Posted 03 July 2020 - 07:24 AM

Hi River-z. 

I would encourage you to have another go splitting Mu Cygni in a few weeks time or when it is higher in your sky. 

On 1st January 2020 I managed to split this true binary at the minuscule power of 140X. 

I could also see its colours: yellow-white and yellow.  

It has been a big favourite of mine for quite a few years now. 

 

Clear skies from Aubrey. 


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#24 flt158

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Posted 03 July 2020 - 02:38 PM

Oh! One more word of warning, to you all. 

It is very easy to bump into Kappa Pegasi which is directly below Mu Cygni by about 4 degrees. 

I once made the mistake and I ended up trying to split that star. bigblush.gif brick.gif  

Kappa Pegasi is 0.5 brighter and it is a lot more difficult to split.  

But now I make sure I have the correct star. coolnod.gif  

 

Best regards from Aubrey. 


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