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(Mostly) Unequal Doubles

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#1 nerich

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Posted 15 July 2020 - 10:12 PM

Hello Friends, 

 

My skies cleared last night for the first time in nearly two weeks. Seeing was only average, unfortunately, but transparency was pretty good. 

 

 

Spurred on by one of Ed's recent posts in his Lyra Doubles thread, I started out with 17 Lyrae (5.3/9.1, 3.2"). At 45x (3.3mm exit pupil) I noted the light yellow color of A, and counted four wide companions, the brightest being D to the northwest. C and F were somewhat dimmer, and formed a line pointing roughly north, while E was to the southeast at about the same distance as D. A little further to the east-northeast was a dim double separated by about 25", which I wasn't able to find in WDS.

Switching to the trusty old University Optics 18mm Ortho for a power of 100x (1.5mm exit pupil), B revealed itself to the west-northwest. At magnitude 9.1 and tucked so close to the primary, I had a tough time reading the color; at times it looked lilac, which in an unequal pairing often translates to an orange star. Unfortunately, I can't confirm my suspicions, as Simbad provides only a G-mag for B. Whatever the spectral type, this is a fine pair. Thanks to Ed for the recommendation!

 

 

Moving east into Cygnus, I located 52 Cygni (4.3/9.5, 6.6"). Unlike my previous target, B shone quite conspicuously at 45x. Bumping the power to 100x gave the miniscule companion a distinct bluish hue next to A's butter yellow. I saw the PA as just north of east, and estimated 80° (WDS says 70°). Switching to the 12.5mm Ortho for a power of 145 (1.03mm), B turned grayish green. Just lovely! I'm attaching some sketches from my gallery. Click for slightly more, but still not great, resolution. 

 

52 Cygni
 
 
 
 
When copying the data for Upsilon Cygni (4.4/10.8, 15.2" and 10, 22.1") into my observing list, I neglected to include the C component – a serendipitous omission. At low power I immediately saw what I thought was B to the south-southwest; as my eye relaxed, a third component, slightly dimmer, suddenly appeared in between the two. What a sight! This was one of those moments of shocking beauty that took my breath away and reminded me of why I went crazy for double stars to begin with. The primary was what I call "lace white," or sort of a creamy color, while my B, which was actually C, was bluish. The real B, at tenth magnitude, had no color, but flickered alluringly in the glare of A. 
 
If you're of the opinion that anything separated by more than a few arc seconds isn't worth passing through your optical chain, I invite you to drop in a low-power eyepiece and survey the scene around Upsilon Cygni. I then invite you, after taking your fill, to contemplate whether chocolate is worth eating and wine worth drinking, though vegetables and clean water are enough to keep you alive.
 
At 100x, I noticed a very dim double to the northeast, with a PA of roughly east. A little searching this morning brought up the designation SLE 383 (10.5/11.9, 15.1"), the discoverer code referring to French astronomer Guy Soulié (1920-2015). Monsieur Soulié seems to be more famous for his asteroid discoveries than his double star observations, with two asteroids, (1736) Floirac and (1918) Aiguillon, credited to him, and a third, (13226) Soulié, named in his honor. While not terribly difficult for 5.9 inches of aperture to make out, SLE 383's two dim components were nevertheless challenging to position accurately in a sketch.
 
 
Upsilon Cygni and SLE 383

 

 

 

 

About five degrees south, and not far from Zeta Cygni, is STF 2762 (5.7/8.1, 3.4"), otherwise known as V 389 Cygni. At low power, potential components were scattered everywhere: I saw one about 50" to the west-southwest, another a similar distance to the east-northeast, and two more trailing a little further behind. 100x revealed a gorgeous golden B component tight to the northwest, its aureate luster brilliant and unmistakable. Another smasher! 

 

Near midnight, my telescope and eye as acclimated as they were going to get, I moved deeper into Cygnus for the challenging STT 387 (7.1/7.9, 0.46"). Of course I wasn't going to "split" this pair with 150mm, but I was curious about what kind of shape I could make out of it. I first got a hint of an elongation, which I saw as roughly southeast, at 145x. Dropping in the 9mm Ortho for a power of 200x (0.75mm exit pupil) didn't show much more detail, but 270x (0.56mm) gave me a very clear egg shape, and allowed me to refine my PA estimate to east-southeast. At 360x (0.42mm), my highest power, I could just make out a defined angle where the spurious disks divided. It certainly wasn't a "notch," as there wasn't any black space attempting to wedge its way between the disks. Rather, B formed an almost rectangular joint against A. In my notes, I described the combined disks as keyhole shaped. With the average seeing not doing me any favors, I struggled to detect any asymmetry at all in the combined first diffraction ring, which was quite round. In all, I spent about 30 minutes on this difficult but invigorating observation. 

If anyone has any more information about this system, please feel free to share it (looking at you, Fred). 

 

 

STT 387
 
 
 
 

It's my habit to end the night with an easy showpiece, and on this night I chose Gamma Delphini (4.4/5, 8.9"). This was an early favorite of mine, and what a work of art it is! To my eye, A is sandstone pink, and B greenish yellow. Astonishingly, I had never taken the time to log Gamma Del's friend, STF 2725 (7.5/8.2, 6.2"), in my notes. Together they form one of the great double-doubles. 

 

Gamma Delphini and STF 2725




That's all for now! As usual, please feel free to comment or to point out any errors. 
 

 


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#2 mauigazer

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Posted 16 July 2020 - 01:21 AM

I made a sketch of STF 2727 back in 2017. I also observed STF 2725 but don't have a sketch of it. Primary as golden yellow and the companion as silver blue.

 

If you don't mind, I'll post my sketch of STF 2727 from that period connecting to My Gallery.

 

12 Del, STF 2727

 

S. McG.


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#3 flt158

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Posted 16 July 2020 - 08:36 AM

Hello, Nick. 

I am so pleased you are managing to get some clear skies in North Carolina. 

I have not had a decent observing session since 24th June! 

That's 3 weeks and a day ago. 

 

However your reports always cheer me up, Nick. 

As you already know, I have observed 17 Lyrae in the past. 

52 Cygni I did split way back in the past too. 

It seems Guy Soulié keeps cropping up every now and again here on the double star forum of Cloudy Nights.smile.gif   

What a pity he's not listed in Burnham. 

 

But STF 2762 is. Sadly I haven't check this triple out. 

 

Upsilon Cygni I have not got to as yet either. 

It seems a real winner to me. 

And that triple star is listed in Burnham. 

 

There clearly are plenty of fascinating doubles and triples to explore in Cygnus. 

 

By the way, there is a slight glimpse of hope of some sort of clear sky tonight Thursday over Dublin, Ireland. 

But I am so skeptical of the 3 weather websites of which I check regularly. 

Twice last week they said we were due to have clear skies over Dublin. 

But they were all 100% wrong. 

Needless to say: if my skies do clear sufficiently, I will be out with my William Optics in good time.   

 

Thankfully I have had plenty of opportunities to observe Gamma Delphini and STF 2725 over many years. 

I even did show these to my wife Valerie when the refractor was new.  

She was thrilled with the sight of the double - double at 112X.  

 

Adios to all, 

 

Aubrey. 


Edited by flt158, 16 July 2020 - 08:39 AM.

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#4 nerich

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Posted 16 July 2020 - 10:43 AM

I made a sketch of STF 2727 back in 2017. I also observed STF 2725 but don't have a sketch of it. Primary as golden yellow and the companion as silver blue.

 

If you don't mind, I'll post my sketch of STF 2727 from that period connecting to My Gallery.

 

 

 

S. McG.

 

Thanks Steve! Great sketch, as always. What a color contrast on this one! 
 

 

 

Hello, Nick. 

I am so pleased you are managing to get some clear skies in North Carolina. 

I have not had a decent observing session since 24th June! 

That's 3 weeks and a day ago. 

 

However your reports always cheer me up, Nick. 

As you already know, I have observed 17 Lyrae in the past. 

52 Cygni I did split way back in the past too. 

It seems Guy Soulié keeps cropping up every now and again here on the double star forum of Cloudy Nights.smile.gif   

What a pity he's not listed in Burnham. 

 

But STF 2762 is. Sadly I haven't check this triple out. 

 

Upsilon Cygni I have not got to as yet either. 

It seems a real winner to me. 

And that triple star is listed in Burnham. 

 

There clearly are plenty of fascinating doubles and triples to explore in Cygnus. 

 

By the way, there is a slight glimpse of hope of some sort of clear sky tonight Thursday over Dublin, Ireland. 

But I am so skeptical of the 3 weather websites of which I check regularly. 

Twice last week they said we were due to have clear skies over Dublin. 

But they were all 100% wrong. 

Needless to say: if my skies do clear sufficiently, I will be out with my William Optics in good time.   

 

Thankfully I have had plenty of opportunities to observe Gamma Delphini and STF 2725 over many years. 

I even did show these to my wife Valerie when the refractor was new.  

She was thrilled with the sight of the double - double at 112X.  

 

Adios to all, 

 

Aubrey. 


Thanks Aubrey! I'd love to hear your report of Upsilon Cyg. It's an elegant object, well suited to the refined tastes of connoisseurs like yourself. 
And Gamma Del: what a way to initiate a new telescope! I bet it was stunning through your WO refractor. 
Wishing you good luck with the weather. 

 


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#5 payner

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Posted 16 July 2020 - 12:44 PM

Enjoyed reading your excellent report, Nick. I have to agree, Gamma Delphini has been a long favorite of mine, too. I enjoy looking at the dolphin on summer evening.


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#6 nerich

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Posted 16 July 2020 - 12:56 PM

Enjoyed reading your excellent report, Nick. I have to agree, Gamma Delphini has been a long favorite of mine, too. I enjoy looking at the dolphin on summer evening.


Thanks for the compliments Randy! Are the skies over the Bluegrass State any better than over here in the Land of the Pines? 



#7 payner

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Posted 16 July 2020 - 04:45 PM

Hi Nick: I believe regionally they are mostly similar. We get those humid, hazy conditions that are murderous on deep sky/transparency, but for planetary and double stars can be an advantage due to stability, as you know. It is acting like we're in the tropics today with on-and-off downpours (as it just started again with this message). I have to admit we did have unusual transparent skies Sunday thru Tuesday (akin to what we may get in October). Always a competition as to whether I can go out and observe; alas, I had to admire those skies for about a half hour each evening naked eye, Hope we have clear skies at least Friday or Saturday. It is premo Jupiter, Saturn and even Mars time and would relish a night soon with the telescope.

PS: I did take a look at 99 Her about a week ago in my 150-mm apo refractor, but did not get a clean split. The seeing was 3/5 and really need a night of at least 4/5 to give it another try. In brief moments I thought I'd see maybe a pimple (at about 440x), but in no way am claiming the secondary, rather attribute it to the (at least) seeing. I believe it is nearing its widest separation over the next ~five years.


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#8 nerich

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Posted 16 July 2020 - 04:56 PM

PS: I did take a look at 99 Her about a week ago in my 150-mm apo refractor, but did not get a clean split. The seeing was 3/5 and really need a night of at least 4/5 to give it another try. In brief moments I thought I'd see maybe a pimple (at about 440x), but in no way am claiming the secondary, rather attribute it to the (at least) seeing. I believe it is nearing its widest separation over the next ~five years.

Thanks for taking a look at it! I'm starting to think that 99 Her might be a bit of a stretch for 6 inches, at least on anything but a perfect night. But it feels soooo close to being possible. I'd like to give it another try on a great night. 


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#9 payner

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Posted 16 July 2020 - 07:10 PM

Agree, I think it is going to take one of those near-perfect seeing evenings. We get some of those and am sure you do, too. It's always about being at the right place at the right time. I have not given up on this one just yet either.


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#10 fred1871

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Posted 17 July 2020 - 09:39 PM

Quote: from #1 above, by Nick:
Near midnight, my telescope and eye as acclimated as they were going to get, I moved deeper into Cygnus for the challenging STT 387 (7.1/7.9, 0.46"). Of course I wasn't going to "split" this pair with 150mm, but I was curious about what kind of shape I could make out of it. I first got a hint of an elongation, which I saw as roughly southeast, at 145x. Dropping in the 9mm Ortho for a power of 200x (0.75mm exit pupil) didn't show much more detail, but 270x (0.56mm) gave me a very clear egg shape, and allowed me to refine my PA estimate to east-southeast. At 360x (0.42mm), my highest power, I could just make out a defined angle where the spurious disks divided. It certainly wasn't a "notch," as there wasn't any black space attempting to wedge its way between the disks. Rather, B formed an almost rectangular joint against A. In my notes, I described the combined disks as keyhole shaped. With the average seeing not doing me any favors, I struggled to detect any asymmetry at all in the combined first diffraction ring, which was quite round. In all, I spent about 30 minutes on this difficult but invigorating observation. 


If anyone has any more information about this system, please feel free to share it (looking at you, Fred). 

 

How could I resist a direct invitation grin.gif 

 

STT 387 is not a double with obscure data to be unearthed. The orbit diagram in the 6th Orbit Catalogue shows a lot of measures over nearly the whole of the calculated orbit, although the early ones have a lot of scatter. 

 

Recent measures, starting with Hipparcos in 1991, are much more consistent. Hipparcos got a separation of 0.653" in 1991; closing since, with Hartkopf in 2006 measuring 0.569", and Tokovinin in 2015 0.488". The WDS "last precise" is 0.434" in 2018. So there's been gradual closing. There is a small difference between the speckle measures and the Ephemeris, for a Grade 2 orbit, of 178 years period, but not enough to be troubling. More like it's needing a small tweak.

 

Given the telescope aperture, 150mm, the separation if taken as 0.46" is 0.5-Rayleigh, and well below Dawes' Limit. So it's no surprise to get only elongation, without notching. Notching would suggest a wider separation, or aberrations perhaps due to seeing.

 

Conclusion - nicely captured as an elongation, Nick; and seeing it separated will of course require more aperture. I don't have any observations of my own recorded for this one. I may try it when Cygnus is above my Northern horizon at a pre-midnight time, later this year. But STT 387 culminates only about 20 degrees from the horizon at my latitude.

 
 
 
 
 

 


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#11 nerich

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Posted 17 July 2020 - 10:36 PM

 

How could I resist a direct invitation grin.gif

 

STT 387 is not a double with obscure data to be unearthed. The orbit diagram in the 6th Orbit Catalogue shows a lot of measures over nearly the whole of the calculated orbit, although the early ones have a lot of scatter. 

 

Recent measures, starting with Hipparcos in 1991, are much more consistent. Hipparcos got a separation of 0.653" in 1991; closing since, with Hartkopf in 2006 measuring 0.569", and Tokovinin in 2015 0.488". The WDS "last precise" is 0.434" in 2018. So there's been gradual closing. There is a small difference between the speckle measures and the Ephemeris, for a Grade 2 orbit, of 178 years period, but not enough to be troubling. More like it's needing a small tweak.

 

Given the telescope aperture, 150mm, the separation if taken as 0.46" is 0.5-Rayleigh, and well below Dawes' Limit. So it's no surprise to get only elongation, without notching. Notching would suggest a wider separation, or aberrations perhaps due to seeing.

 

Conclusion - nicely captured as an elongation, Nick; and seeing it separated will of course require more aperture. I don't have any observations of my own recorded for this one. I may try it when Cygnus is above my Northern horizon at a pre-midnight time, later this year. But STT 387 culminates only about 20 degrees from the horizon at my latitude.

 

Thanks so much Fred! This is just the kind of detail I was looking for. 
And yes, I'd love to hear what you can make out of it, if you think the low altitude won't interfere too much with your observation. 




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