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Five More Pairs in Cygnus

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#1 nerich

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Posted 03 July 2020 - 02:51 PM

Hello Friends, 

Allow me to share a few observations from another pleasant bounce around Cygnus. My conditions last night in Greensboro were good: average transparency, excellent seeing, and the gibbous moon favorably hidden away behind some trees to the South, with minimal intrusion upon my work.

I began in the northern portion of the Swan's territory with STF 2658 (7.2/9.4, 5.4"). The low power view with the 32mm Plössl at 56x (2.7mm exit pupil) revealed a lovely triple: A was off-white, B tucked up neatly against the primary and a strong orange despite its magnitude, and C to the southwest with a clear bluish-white color by comparison. Raising the power warmed up A's hue to beige. A fine and unexpectedly colorful trio. 

My eye and telescope in good working order, I moved southwest to Delta Cygni (2.9/6.3, 2.8"), which I haven't observed since August of 2018. I first caught a glimpse of B at 90x (1.7mm exit pupil), where it formed nothing more than a persistent lump of extra brightness attached to A and pointing southwest. 120x (1.25mm) gave B more definition, and at 145x (1.03mm) the view was stunning: B was a perfectly round point that remained almost impossibly still as A's diffraction rings undulated around it. A was brightest white color I can remember seeing recently, and B very slightly yellowish. I'm still in the honeymoon phase with my new Maksutov, and I was equally stunned by the optics of this excellent instrument: this is the best diffraction pattern I've seen on any obstructed telescope. It looked almost digitally rendered!

Hopping back northeast, I centered STF 2741 (5.9/6.8, 2") in the finder. This exquisite pair is another one of William Herschel's discoveries, and is H I 97 in his catalog. 56x gave me an elongation pointing north/northeast, and 72x notched the pair. At 90x they were split on and off, but I required 120x to put consistent black space between them. What a gorgeous pair! Very highly recommended.

After a detour to 16 Vul (see my other thread for the report), I returned to Cygnus for the evening's most difficult pair: 60 Cygni (5.4/9.5, 2.9"). In the low-power view, I noticed a brightish and quite wide double to the south; this was the AC pair of S.W. Burnham's no. 1138 (the AB pair is separated by a mere 0.15"). Returning my focus to 60 Cyg, I slowly raised the power, looking carefully for any sign of the elusive companion. 72x, 90x, and 120x gave me nothing, but immediately upon reaching focus at 145x I saw a ghostly grey spot to the south/southeast. At this power I could hold it about 50% of the time, but 200x (0.75mm) brought B out more clearly. A moderately difficult object, requiring magnification and a little patience.

I always like to end with an easy and pretty object, and on this occasion 61 Cygni (5.2/6.1, 32"), Piazzi's famous flying star, fit the bill nicely. This is a stunning pair even in the finder (my "finder" in this case being my 80mm Stellarvue with a 40mm Plössl, for a magnification of 19x). At all powers I saw the same color contrast: A was coral pink, and B brass-colored. What an extravagantly beautiful pair of K-type stars!

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

 


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#2 The Ardent

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Posted 03 July 2020 - 04:25 PM

In 2013 at Staunton River Star Party, I "discovered" STT 410 (HR 7911 / V2130 Cyg) an almost equal pair 0.9" apart. Using 180x in my 18" dob, just scanning Cygnus starfields. Its located about halfway between Gamma and Nu Cyg. 

 

Another favorite is 29 Cygni / ENG 72 Its a wide binocular double and anchor of a large prominent curl asterism in the rich Milky Way. 


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#3 rugby

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Posted 03 July 2020 - 05:23 PM

Thanks to Nerich and The Ardent for two wonderful star trails to follow. The choices and decisions that make up the writing are not easy and reflect an obvious artistic merit. I will be observing these pairs tonite under a very bright moon.


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#4 chrysalis

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Posted 03 July 2020 - 05:43 PM

I love the look of 61 Cygni (STF2758) in my eyepiece. I must admit I've never noticed a color difference, both appearing tangerine-colored to me, but I will look more closely next time! Thanks for great report!


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#5 nerich

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Posted 03 July 2020 - 05:56 PM

I love the look of 61 Cygni (STF2758) in my eyepiece. I must admit I've never noticed a color difference, both appearing tangerine-colored to me, but I will look more closely next time! Thanks for great report!

 

Thanks Mark! It's such a great pair, isn't it? 

It looks like there's not much of a spectral difference between them: A is K5 and B K7. The color difference I perceived is probably at least partly due to magnitude. Either way, I definitely got the feeling that A was a little pinker and B a little greener, though both in the orange category. 

By the way, if you haven't seen this incredible time lapse, give it a quick look: 

https://commons.wiki...oper_Motion.gif


Edited by nerich, 03 July 2020 - 05:56 PM.

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#6 chrysalis

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Posted 04 July 2020 - 05:21 AM

Thanks Mark! It's such a great pair, isn't it? 

It looks like there's not much of a spectral difference between them: A is K5 and B K7. The color difference I perceived is probably at least partly due to magnitude. Either way, I definitely got the feeling that A was a little pinker and B a little greener, though both in the orange category. 

By the way, if you haven't seen this incredible time lapse, give it a quick look: 

https://commons.wiki...oper_Motion.gif

That is cool!! In fact, at about 11.4 LY, I suspected there might be some sort of video like this, so thanks for sending!! And...I hope my old eyes can perceive the shade difference next time I observe this lovely pair!


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#7 flt158

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Posted 04 July 2020 - 07:20 AM

Good day to all.

I feel young again! I've just had a haircut! bigshock.gif

And the queue was too bad.

I thought barbers had become extinct. shocked.gif

 

As ever, here is a big thank-you to you, Nick, for this new report! applause.gif 

Delta Cygni or Rukh is a big favourite of mine as has been over the last 30 years. gramps.gif lol.gif

I remember the nights I needed over 200X to split it with an 8.75" reflector. 

But thankfully, it is now much easier. 

140X is enough. Or even 112X when the winds die down and the sky is better. 

 

I never knew 61 B Cygni was a K7 star. 

I haven't observed for about 3 or 4 years. 

So when I get the time to observe it, it could be one of those almond brown stars I often seek after. 

My special thanks to Nick for pointing it out to us.

 

Rumour has it I might have clear skies for tomorrow night Sunday. 

It has been 10 long nights since I have had an observation session. Too much cloud. cloudy.gif

The carbon star U Lyrae has become brighter recently. 

And I have a prepared map for it. 

 

Clear skies to all from Aubrey. 


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#8 chrysalis

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Posted 04 July 2020 - 08:17 AM

 

So when I get the time to observe it, it could be one of those almond brown stars I often seek after

 

Aubrey, have you observed 17 Virginis? The secondary always struck me as brownish...


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#9 flt158

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Posted 04 July 2020 - 09:40 AM

I haven't, Mark. 

And I am terribly sorry to say I won't see Virgo until spring 2021. 

Both Guide 9.1 DVD and Burnham say that 17 B Virginis is dK5.  

As my William Optics 158 mm apo is a great killer of false colours, it would be interesting to see what the colours are next year. 

And I am very much capable of observing 17 Vir. 

Its altitude is higher than Porrima (Gamma Vir).  

So I thank you for drawing my attention to it. 

 

Best regards to you, Mark. 

 

Aubrey.  


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