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Observation Gamma andromedae AB (9,6") +BC (0,16")

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#1 Konstantin 1980

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Posted 12 September 2019 - 09:29 AM

fifth day  is a very calm atmosphere. I try these days to observe all the most complex objects that are visible in the sky. I watch the gamma of Andromeda for the third day in a row, and every day I see the elongation of component B. I have repeatedly seen such close pairs, although there were not many. Every day I try to double-check this observation to avoid mistakes. But every day I see the same thing, so I can say that the winners of component C are visible with confidence. The elongation is small, but it is fixed very well in such a calm atmosphere. And is constantly visible. I made a small drawing of what I seeGAM ANDRM.png


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#2 rugby

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Posted 15 September 2019 - 08:19 PM

My hat is off to you Konstantin 1980 for this observation. Can anyone confirm the accuracy of 0.16? 



#3 fred1871

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Posted 15 September 2019 - 09:23 PM

The accuracy of 0.16" is not really in question. The orbit of Gamma And BC is well-enough known for that to be a good number. The question is how someone has the eyesight to see a disturbance in the diffraction image that translates to an elongation, when the telescope used has a Rayleigh criterion of 0.543", so that it is detection at 0.3-Rayleigh for 0.16". The usual detection limit is around 0.5-Rayleigh, with some observers using moderate to small scopes achieving 0.4-Rayleigh.

 

Christopher Taylor in his well-known discussion of limits of detected elongation in his article in Bob Argyle's book Observing and Measuring Visual Double Stars, claims 0.4-Rayleigh with a 12.5-inch Newtonian (detection at 0.175"). That was with 825x. Taylor was optimistic that somewhat better might be achieved, though without achieving it himself. His hoped-for level of detection was about 0.13", which for 12.5-inches is 0.3-Rayleigh. It isn't clear from his article what he based this on, apart, perhaps from a feeling that the closest pair he'd seen elongated was not as near the limit of perception as to suggest one couldn't go further.

 

Seeing conditions, even with near-perfect (as estimated) seeing appear to set more stringent limits with larger scopes. It's never as steady as hoped. Around 0.6-Rayleigh is usual for the big refractors (24-inch to 40-inch). Couteau got to 0.5-Rayleigh with the Nice Observatory 20-inch. Various observers have recorded 0.4-Rayleigh with smaller scopes, as per Taylor above. RTA Innes, notable for his Southern Hemisphere double star work (1890s to 1920s), found a detection limit around 0.4-Rayleigh with a 9-inch refractor.

 

So the answer for 0.3-Rayleigh detection seems most likely to be exceptional eyesight, in conditions of "as good as it gets" atmospheric steadiness. The use of binocular viewing may well help too. All the observers I'm familiar with who observed exceptionally close pairs (for the aperture) were using monocular vision.


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#4 rugby

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Posted 16 September 2019 - 10:33 PM

Given that seeing is ideal and the observer is experienced, sightings of pairs below the rayleigh limit are not rare. Like you Fred 1871 my eyesight is only average. But look again at an observation I made of Stt381 in Aquila in July this year. I suspected strongly that the diffracton disc was irregular  in the correct PA. which for an 8-inch was .6 Rayleigh. Perhaps Constantin would try his hand on this one.



#5 RadioAstronomer

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Posted 17 September 2019 - 12:17 AM

The accuracy of 0.16" is not really in question. The orbit of Gamma And BC is well-enough known for that to be a good number. The question is how someone has the eyesight to see a disturbance in the diffraction image that translates to an elongation, when the telescope used has a Rayleigh criterion of 0.543", so that it is detection at 0.3-Rayleigh for 0.16". The usual detection limit is around 0.5-Rayleigh, with some observers using moderate to small scopes achieving 0.4-Rayleigh.

 

Christopher Taylor in his well-known discussion of limits of detected elongation in his article in Bob Argyle's book Observing and Measuring Visual Double Stars, claims 0.4-Rayleigh with a 12.5-inch Newtonian (detection at 0.175"). That was with 825x. Taylor was optimistic that somewhat better might be achieved, though without achieving it himself. His hoped-for level of detection was about 0.13", which for 12.5-inches is 0.3-Rayleigh. It isn't clear from his article what he based this on, apart, perhaps from a feeling that the closest pair he'd seen elongated was not as near the limit of perception as to suggest one couldn't go further.

 

Seeing conditions, even with near-perfect (as estimated) seeing appear to set more stringent limits with larger scopes. It's never as steady as hoped. Around 0.6-Rayleigh is usual for the big refractors (24-inch to 40-inch). Couteau got to 0.5-Rayleigh with the Nice Observatory 20-inch. Various observers have recorded 0.4-Rayleigh with smaller scopes, as per Taylor above. RTA Innes, notable for his Southern Hemisphere double star work (1890s to 1920s), found a detection limit around 0.4-Rayleigh with a 9-inch refractor.

 

So the answer for 0.3-Rayleigh detection seems most likely to be exceptional eyesight, in conditions of "as good as it gets" atmospheric steadiness. The use of binocular viewing may well help too. All the observers I'm familiar with who observed exceptionally close pairs (for the aperture) were using monocular vision.

Totally agree. Let me add this chart from Couteau's book Ces astronomes fous du ciel : Ou l'histoire de l'observation des étoiles doubles with the resolving power vs inches of the instrument. He claims that Burnham has the record with the discovery of the companion of Rigel B. He also mentions that smaller apertures are more likely to deeper under the resolving power than larger apertures.

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  • Screen Shot 2019-09-16 at 7.48.39 PM.jpg

Edited by RadioAstronomer, 17 September 2019 - 12:18 AM.

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#6 azure1961p

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Posted 22 September 2019 - 07:15 PM

LOL.



#7 Bigzmey

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Posted 24 September 2019 - 04:35 PM

Given that seeing is ideal and the observer is experienced, sightings of pairs below the rayleigh limit are not rare. Like you Fred 1871 my eyesight is only average. But look again at an observation I made of Stt381 in Aquila in July this year. I suspected strongly that the diffracton disc was irregular  in the correct PA. which for an 8-inch was .6 Rayleigh. Perhaps Constantin would try his hand on this one.

For the experienced observer pushing below rayleigh limit (within reasonable) with a smaller scope is no biggy. But with larger scopes and tighter separation things get tougher. For 0.16" it is not just the scope and the eye, but the seeing should be unbelievably fantastic.

 

In my heck of the woods seeing hardly ever drops below 1", so I get maybe couple of shots per year at 0.5-07" splits.

 

I would question myself in such a case. But hey, it is Konstantin's call. :D



#8 Bigzmey

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Posted 24 September 2019 - 04:48 PM

OK, it is not just me. Here is what Wikipedia has to say on the subject.

 

"The best conditions give a seeing disk diameter of ~0.4 arcseconds and are found at high-altitude observatories on small islands such as Mauna Kea or La Palma.

Seeing is one of the biggest problems for Earth-based astronomy. While large telescopes have theoretically milli-arcsecond resolution, the real image is limited to the average seeing disc during the observation. This can easily mean a factor of 100 between the potential and practical resolution. Starting in the 1990s, new adaptive optics have been introduced that can help correct for these effects, dramatically improving the resolution of ground-based telescopes."



#9 Nucleophile

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Posted 11 October 2019 - 09:46 AM

Given that seeing is ideal and the observer is experienced, sightings of pairs below the rayleigh limit are not rare. Like you Fred 1871 my eyesight is only average. But look again at an observation I made of Stt381 in Aquila in July this year. I suspected strongly that the diffracton disc was irregular  in the correct PA. which for an 8-inch was .6 Rayleigh. Perhaps Constantin would try his hand on this one.

Hi Rugby,

 

I am a bit confused by what you wrote for STT 381.  Stelle Doppie lists the last precise separation (2015) as 14.576"

 

Were you referring to a different system?  I am interested in knowing because I am keen to observe any stars that fit the separation profile you mentioned in support of  my 8 inch reflector observation studies.

 

Thanks,

 

-Mark M



#10 Astrojensen

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Posted 11 October 2019 - 10:57 AM

OK, it is not just me. Here is what Wikipedia has to say on the subject.

 

"The best conditions give a seeing disk diameter of ~0.4 arcseconds and are found at high-altitude observatories on small islands such as Mauna Kea or La Palma.

Seeing is one of the biggest problems for Earth-based astronomy. While large telescopes have theoretically milli-arcsecond resolution, the real image is limited to the average seeing disc during the observation. This can easily mean a factor of 100 between the potential and practical resolution. Starting in the 1990s, new adaptive optics have been introduced that can help correct for these effects, dramatically improving the resolution of ground-based telescopes."

There are NUMEROUS reports throughout the history of visual observing, where the seeing has been much better than 0.4". Thomas Cave's observation of Mars with the 100" Hooker telescope at 3,200x comes to mind. He said that even at that magnification, the image was completely motionless and stunningly sharp. There was a short S&T article about it many years ago. 

 

 

Clear skies!
Thomas, Denmark


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#11 fred1871

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Posted 11 October 2019 - 08:49 PM

The seeing disk diameter studies give numbers that are integrated averages over time. "Lucky imaging" is one of the techniques that works better than that for high resolution - fraction of a second exposures, the sharpest of them enabling diffraction limited rather than seeing limited detail or resolution.

 

It's common to find resolutions well below 0.4" in the double star literature with observers using large telescopes. The eye tends to see past the seeing on good nights, allowing Rayleigh or Dawes levels of resolution with scopes bigger than, say 20-inches (50cm). I've done a lot of work on the measures by Aitken, Husey, van den Bos, Rossiter, etc, and measures at 0.20" and closer are common - these observers used scopes in the ~70-90cm aperture range.

 

In my own visual observing I've seen clear elongation - in PA checked later - of equal doubles around 0.35", using a mere 21cm Mewlon reflector. Numbers from Grade 1 orbits ephemeris, and sometimes confirmation via speckle with a large scope.

 

The other common techniques for "seeing through the seeing" are adaptive optics, and speckle interferometry. Hubble is not the only way to break the 0.4" limit.


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#12 rugby

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Posted 11 October 2019 - 10:18 PM

Mark M    I meant STT380  not STT381.    I apologize for the error


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#13 Bigzmey

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Posted 14 October 2019 - 04:48 PM

The seeing disk diameter studies give numbers that are integrated averages over time. "Lucky imaging" is one of the techniques that works better than that for high resolution - fraction of a second exposures, the sharpest of them enabling diffraction limited rather than seeing limited detail or resolution.

 

It's common to find resolutions well below 0.4" in the double star literature with observers using large telescopes. The eye tends to see past the seeing on good nights, allowing Rayleigh or Dawes levels of resolution with scopes bigger than, say 20-inches (50cm). I've done a lot of work on the measures by Aitken, Husey, van den Bos, Rossiter, etc, and measures at 0.20" and closer are common - these observers used scopes in the ~70-90cm aperture range.

 

In my own visual observing I've seen clear elongation - in PA checked later - of equal doubles around 0.35", using a mere 21cm Mewlon reflector. Numbers from Grade 1 orbits ephemeris, and sometimes confirmation via speckle with a large scope.

 

The other common techniques for "seeing through the seeing" are adaptive optics, and speckle interferometry. Hubble is not the only way to break the 0.4" limit.

Resolving slightly below Rayleigh limit on a night of good seeing with a small scope - done that. smile.gif Resolving at Rayleigh limit with a large scope on a night of excellent seeing - difficult, but experienced observer may get lucky. This is what you are referring to in your example, since Rayleigh limit of 70cm is about 0.2". In this case however 0.16" is far below 0.46" limit of 25cm scope. So, allow me to be skeptical. 


Edited by Bigzmey, 14 October 2019 - 04:48 PM.


#14 mccarthymark

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Posted 14 October 2019 - 05:33 PM

The Rayleigh resolution criterion refers to seeing split, eg. the minimum separation needed to see two distinct star images) in equal magnitude stars.  For Konstantin's 254mm scope it is 138/254 = 0.543 arcseconds (").  Abbe resolution limit is 113/254 = 0.449".  Sparrow is 108/254 = 0.425".  As Bruce MacEvoy states in his introduction to the CDSA, "Many skilled observers can detect an equal magnitude binary as an elongated, "egg shaped" or "rod shaped" star at a separation that is nearly half the Abbe limit" (my emphasis).  That would be 0.2245".  

 

In the original post Konstantin did not claim to split this pair (eg Rayleigh).  He tells very clearly he is perceiving the elongation -- meaning he's exceeding, by a mere 0.0645", the half-Abbe limit.  He also made observations over three nights to confirm.  With the perfect seeing he reports, I believe his observation.

 

I have no skepticism about Konstantin's observations, and I'm glad he is sharing them with us here.


Edited by mccarthymark, 14 October 2019 - 11:45 PM.

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#15 fred1871

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Posted 14 October 2019 - 11:44 PM

The Rayleigh resolution criterion refers to seeing split, eg. the minimum separation needed to see two distinct star images) in equal magnitude stars.  For Konstantin's 254mm scope it is 138/254 = 0.543 arcseconds (").  Abbe resolution limit is 113/254 = 0.449".  Sparrow is 108/254 = 0.425".  As Bruce MacEvoy states in his introduction to the CDSA, "Many skilled observers can detect an equal magnitude binary as an elongated, "egg shaped" or "rod shaped" star at a separation that is nearly half the Abbe limit" (my emphasis).  That would be 0.2245".  

 

In the original post Konstantin did not claim to split this pair (eg Rayleigh).  He tells very clearly he is perceiving the elongation -- meaning he's exceeding, by a mere 0.0645", the Abbe limit.  He also made observations over three nights to confirm.  With the perfect seeing he reports, I believe his observation.

 

I have no skepticism about Konstantin's observations, and I'm glad he is sharing them with us here.

I'm still not certain why Bruce McEvoy decided to re-introduce the Abbe resolution limit, a concept more often discussed in microscopy than in astronomy regarding telescopes. The Abbe limit is 0.8 of the Rayleigh criterion, and approximates to what we could could the "notched double criterion" in double stars with equal pairs. Consequently, Bruce's point about "nearly half the Abbe limit" corresponds to nearly 0.4-Rayleigh. A level I've commented on before as achievable for detecting out of round star images, at least with small to moderate apertures. Seeing more strongly limits larger scopes.

 

Regarding "a mere 0.0645", the significant factor is proportionality - its size relative to a criterion. With a 3 arcsecond double that amount is insignificant; with a 0.03 arcsecond double (such as is detectable and measurable with speckle interferometry on 4-metre scopes) it becomes huge. Here, it represents a reduction of nearly 30% below the 0.5-Abbe criterion. In terms of Rayleigh, as noted previously, it's 0.3-Rayleigh. For Abbe, it's ~0.35-Abbe, quite a way from "approaching" 0.5-Abbe.

 

As I've commented at various times, although there are issues regarding the shape that the combined star disks take once one gets below 0.5-Rayleigh, there's not an obvious reason to doubt that some visible signifiers could be present at extremely close separations, down to some extinction point that's below 0.5-Rayleigh. Eventually the optics will not - because they cannot - provide any hint of non-singularity. Exactly where that occurs, even in terms of exceptional eyesight, is something I've not seen research on. Couteau in his book only goes to 0.5-Rayleigh. Practical experience shows some observers are getting to 0.4-Rayleigh. I've not tried for that, although I recently got 0.45-Rayleigh on Zeta Sagittarii with my 140mm refractor (it simply happens to be at that separation at present in relation to that aperture). 

 

Does anyone know of a research paper that examines the isophotes of closer and closer doubles in relation to Rayleigh? - it would be an extended version of what Couteau did. I expect he was content with a 0.5-Rayleigh limit because it matched what he'd found possible with the Nice Observatory 50cm refractor; and because the optical parameters in the study he presented led to an extinction point at that 0.5R level. Given the practical experience of some observers going somewhat beyond that, that is, closer, there's a further optical-theory study to carry out, going beyond that "limit" instead of stopping there.


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#16 mccarthymark

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Posted 14 October 2019 - 11:59 PM

I guess I am just exasperated at the incredulity Konstantin gets for his observations.  The elongation he notices on this one is so very subtle and fleeting I doubt I could possibly notice it.  But he is consistent (how many of us have ever spent three nights to confirm an observation?) and sincere.  Pushing the limits, to be sure, which is what makes his observations so exiting.  I do not doubt him; he has no reason to make this up.  He may be a talent on the level of Burnham and Barnard and should be celebrated.  It would be nice to have science back up the claim but as we know the observer's talent can't be so easily quantified.  I'm willing to let that factor tip the scale.


Edited by mccarthymark, 14 October 2019 - 11:59 PM.

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#17 rugby

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Posted 15 October 2019 - 08:11 AM

I would like to hear more from Konstantin about the reactions to his observation



#18 Bigzmey

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Posted 15 October 2019 - 01:55 PM

I guess I am just exasperated at the incredulity Konstantin gets for his observations.  The elongation he notices on this one is so very subtle and fleeting I doubt I could possibly notice it.  But he is consistent (how many of us have ever spent three nights to confirm an observation?) and sincere.  Pushing the limits, to be sure, which is what makes his observations so exiting.  I do not doubt him; he has no reason to make this up.  He may be a talent on the level of Burnham and Barnard and should be celebrated.  It would be nice to have science back up the claim but as we know the observer's talent can't be so easily quantified.  I'm willing to let that factor tip the scale.

I don't believe anybody here implies that Konstantin is insincere, or making up the stuff on purpose . But in any experimental observation you can get real data and artifacts. We are talking about 800x magnification here.  He has a mass-produced mirror. Any imperfections will show up at this power. Any instrument optical or other has the working range. He is pushing his instrument well beyond designed resolution range, where signal to noise ratio is extremely small. If I would see something like this I would be skeptical of myself. If I would share it with others, I would be hey guys I saw this do you think it is real or bull...? And if other experienced observers say most likely bull..., I would not make a big fuss of it. smile.gif


Edited by Bigzmey, 15 October 2019 - 02:20 PM.

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#19 Konstantin 1980

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Posted 16 October 2019 - 07:44 AM

I have been watching binary stars for a long time. This forum has many of my observations of cramped binary stars. I posted a few observations here, where the separation is about 0.16. These are ordinary observations, I’m used to them and don’t perceive them as something special. For example, I will see ovality when I divide by 0, 22 ", it is very easy for me. So I switched to closer ones to find out how far you can go. At the moment, my best result is for a 254 mm telescope. 0.13 "spacing when I was able to catch the difference from the circle. I am not very sure of this observation, because I could not repeat it (there were no such good conditions, and this star also changed its position).
Since 6 years I have been fond of astronomy, then I already made my first notes (about a meteor). I am now 39 years old, and I have been watching the sky for 33 years. Of these, from 8 to 14 years old - on improvised telescopes (their lenses for glasses). From 14 to 19 years in small telescopes (about 90 mm). From 20 to 32 years in a telescope with a diameter of 110 mm. And from 32 to 39 years in a telescope with a diameter of 254 mm. Since I didn’t have much choice and the telescopes were bad for a long time, I spent a lot of time to see something there at all. As a result, I gained a lot of experience, and when I acquired a high-quality 254 mm telescope, I began to see more than others. It was unexpected even for me. Some people did not trust my observations, but I understand them, I would probably react in the same way. I am very persistent and patient (I am a musician by profession, and I can repeat the montony work for a long time and achieve results, while other people would not have had patience for a long time). It also helps me with observations. I can look at one star for 3 hours, and I do not find it uninteresting. Even a frost of 30 degrees is not an obstacle for me, if I have the mood and the desire to watch. I live in my house , I can pack up in 5 minutes and already observe the sky. I don’t have to go anywhere. It is very convenient. Therefore, I do not miss interesting events and a good atmosphere.


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#20 Konstantin 1980

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Posted 16 October 2019 - 07:55 AM

This is a separate shot from a video that I shot on a friend’s camera when it was a day with a calm atmosphere. We have such days quite often, and this is not the best image, it happens and is noticeably better.кратер клавий.jpg



#21 rugby

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Posted 16 October 2019 - 09:32 AM

Thank you Konstantin 1980 for your response. 




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