Author Topic: Super Limits  (Read 456 times)

chlorleifilwhirl

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Re: Super Limits
« Reply #30 on: January 31, 2018, 03:18:07 AM »
Sometimes I wonder if being critical of your own observations, specifically to rule them spurious, is simply a means of self policing and conforming to what others might expect us to see. Wouldn't wanna rock any boats.

Okay, so no one is going to sketch the Hubble deep field, we can be pretty sure of that. But we might see a dim star once in a while. I've seen eye flashes from time to time, but none of them have ever been memorable enough to include in a sketch or to linger in curiosity for long periods of time. Yea, even when they are, there is still sufficient doubt to simply leave the sighting as a curious thing.

But doubt is not proof, either, any more than our mind tricks and optical illusions are proof the thing was not seen if only for a very rare instant. There may well be sufficient leeway in the limits to allow something extraordinary from time to time. It won't be incredibly extraordinary, but it might be marginally so. And we might even expect something just beyond a limit to appear just as it's described: faint, fleeting, and hardly repeating.

Just mulling over the topic, thinking out loud.

John Pfister

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Re: Super Limits
« Reply #31 on: January 31, 2018, 12:42:03 PM »
One can hold any sort of opinion they wish as to how things work or what is possible and it is clear that many here do, Pete. However, science is based on repeatable observational fact. Neither unsupported personal opinion, nor highly improbable individual "sightings" of objects/features clearly beyond tested human limits under given circumstances carries weight. It is only that on these amateur forums where most folks are (1) willing to totally accept anything claimed (2)too timid to question reports concerning implausible/unsubstantiated sightings or (3) don't fully understand the way vision, optics and atmospherics work that they thrive.

Quite honestly, numerous claims of extreme sightings and limits are a relative new aspect of the hobby, although there have always been occasional examples (see Dr. Joseph Ashbrook's wonderfulThe Astronomical Scrapbook, chapters 19, 21 and 62). Actually, the kind of numbers one see's today did not arise until following the advent of internet forums, as I've mentioned here previously. The phenomena also seems to have been boosted by more and more observers going to the eyepiece after repeatedly consulting the details shown on deep printed or on-line images of objects when planning their nightly program. Some will actually bringing such material right to the eyepiece to compare against! Little wonder then that they believe they can identify all manner of absurdly subtle details with their often under-sized optical systems! In such situations of influence the observer is very likely to "see" anything he wishes too...although it can be totally imaginary. Too many of us think we are objective in our observations when in fact we are just as susceptible as any layman to being influenced by what we've seen, read and subconsciously recall in the way of descriptions and images. It is this lack of objectivity demonstrated by most hobbyists that has resulted in the professionals' very low opinion of us and their unwillingness to accept amateur data as being the least bit reliable.

BrooksObs

John Pfister

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Re: Super Limits
« Reply #32 on: February 02, 2018, 04:46:19 PM »
Yeah, but don't forget that the observer has the advantage of knowing something is there, unlike the discoverer.
When I was young, the Veil nebula was something that could only be photographed or seen in large observatory scopes.
Then along came Jack Marling, with his narrowband filters, and suddenly the Veil was something that could be seen in 4",
no, 3", no 2", and then (using a filter) the naked eye!
So someone with a very large scope (or a photograph) has to pioneer the way.
I find the outer spiral arms of M81 to be difficult in my 12.5", but they occasionally show up.
I took a photo to the field with me to get their orientations and to see if I could see Holmberg IX (I couldn't).
Looking at the photo told me that something I might have dismissed as spurious was, indeed, a feature of the spiral arms.
It was only very intermittently visible at all.

And I have pushed similar observing limits a few hundred times over the years by first reading about someone else's technique
or a limit sighting in a similarly-sized scope. And a photograph can reveal what is illusion and what is real.

There have been many times I have not seen a galaxy, only to walk over to a 28" scope nearby to look at the same field, seen the galaxy,
then walked back to the 12.5" and seen the galaxy as an averted vision object, winking in and out. Had I not seen it in the 28",
I would have dismissed it as spurious in the 12.5" because it was so faint and intermittently visible.
In the first case, I would have said it was "below the limit of my scope". In the second case, I would have said it's "at the limit of my scope".

So I don't necessarily dismiss the sighting of an extremely faint or difficult target just because I haven't seen it, any more than someone
else should dismiss my sighting of something that seems a little too faint for my size of scope.

On the flip side is the concept that though the actual limit of a scope is somewhat nebulous (pun intended), it isn't going to suddenly be
exceeded by, say, 1.5 magnitudes. Unless, as has been pointed out, the magnitude in books is wrong. If I can only see a few stars beyond
magnitude 17 under exceptional circumstances, I am not going to suddenly see stars of magnitude 19.
But extended deep sky objects are extremely sensitive to atmospheric transparency and sky darkness. I do not find it remarkable
that someone observing under darker and more transparent skies would see beyond what I have been able to see.
Any more than I would find it remarkable that someone observing in the swamp at sea level in the summer time in a light-polluted sky
might find my observations incredulous.

Trust, but verify is a good rule when seeing things at the very limit of the scope. Computer atlases, photographs, on line references, etc. all
come into play to verify a "limit" observation. The only difficulty is in trusting the magnitude of the observation. That could be the difficult part
of verification.

russnappditcva

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Re: Super Limits
« Reply #33 on: February 02, 2018, 08:58:37 PM »
Don Pensack wrote:
<p class="citation">QuoteWhen I was young, the Veil nebula was something that could only be photographed or seen in large observatory scopes.[/quote]

Not when I was a kid! As a young teen-ager (well before nebula filters were created), I had just finished building my 8 inch f/7 Newtonian and had it out in my magnitude 5.7 back yard. I had seen the Veil marked in my 1964 edition of Donald Menzel's FIELD GUIDE TO THE STARS AND PLANETS, so somewhat tentatively, I pointed the scope at the right spot and took a look in. I was floored to see a ghostly irregular band-like arc running across the field, which pretty much made my night. Not long after that, I had heard from one of our veteran club members that the main Veil (NGC 6992) arc was visible in a pair of 10x50 binoculars which I personally verified later on that this was possible. Filters made it a lot easier to see, but well before filters, many observers had reported that the object was visible in rather modest apertures. In the case of faint stars, I have to see them more than a quarter of the time I am looking for them before I consider the sighting firm. Even then, there are exceptions to this (as in the case for the central star in M57). For decades, I completely wrote-off amateur sightings of the Ring's central star until one night in a 20 inch where I learned the truth about seeing faint stars in nebulosity. Time and observing experience almost always reveals what is possible and what may not be, but hard and fast limits may not be all that hard and fast. Clear skies to you.

Christopher Bryant

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Re: Super Limits
« Reply #34 on: February 09, 2018, 01:03:49 AM »
Quote
One can hold any sort of opinion they wish as to how things work or what is possible and it is clear that many here do, Pete. However, science is based on repeatable observational fact. Neither unsupported personal opinion, nor highly improbable individual "sightings" of objects/features clearly beyond tested human limits under given circumstances carries weight. It is only that on these amateur forums where most folks are (a) willing to totally accept anything claimed ( B) too timid to question reports concerning implausible/unsubstantiated sightings or © don't fully understand the way vision, optics and atmospherics work that they thrive.

Quite honestly, numerous claims of extreme sightings and limits are a relative new aspect of the hobby, although there have always been occasional examples (see Dr. Joseph Ashbrook's wonderfulThe Astronomical Scrapbook, chapters 19, 21 and 62). Actually, the kind of numbers one see's today did not arise until following the advent of internet forums, as I've mentioned here previously. The phenomena also seems to have been boosted by more and more observers going to the eyepiece after repeatedly consulting the details shown on deep printed or on-line images of objects when planning their nightly program. Some will actually bringing such material right to the eyepiece to compare against! Little wonder then that they believe they can identify all manner of absurdly subtle details with their often under-sized optical systems! In such situations of influence the observer is very likely to "see" anything he wishes too...although it can be totally imaginary. Too many of us think we are objective in our observations when in fact we are just as susceptible as any layman to being influenced by what we've seen, read and subconsciously recall in the way of descriptions and images. It is this lack of objectivity demonstrated by most hobbyists that has resulted in the professionals' very low opinion of us and their unwillingness to accept amateur data as being the least bit reliable.

BrooksObs


Hi BrooksObs,

I'vebeen right with you in your previous comments, but with your above post my willingness to totally accept anything claimed wore off a little. I have a few questions and comments about your claims:

Do most people on amateur forums really accept anything claimed or are too timid to question them? How do you know that?
Are there really numerous claims of extreme sightings in amateur astronomy? If so, where are they being made? Many of the comments I read on CN are from people complaining about not seeing as much as they’d hoped to, but then I don’t read every post. Extreme claims seem quite rare in my experience.
Do you really consider consulting deep images at the eyepiece as proof that amateur observers are so weak willed that we’ll see anything we want to? If so, what is your evidence for this claim? If it really works this way, why can’t I see Abell 85?
What’s your evidence that professional astronomers have a low opinion of amateurs because we lack objectivity? What type of amateur research are you referring to? How do you account for the successful pro-am collaborations that are in the news every so often? Do you have knowledge of failed attempts?

What is your process to verify a visual observation?

Objectivity in a nearly purely subjective hobby such as visual astronomy takes vigilance, but in my experience amateur observers are not given to extreme claims and are quite conservative in what they report - even those who use deep photos as references at the eyepiece. If there’s doubt in an observation, they’ll say so. That’s not to say that therearen'tthose who say they see outrageous things – I once encountered an older gentleman who said he could seestars naked eye in the daytime and pointed to Sirius high in the northeast sky on an sunny August afternoon as proof.

Importantly, I accept the possibility that your experiences are completely in line with whatyou'vewritten above, but they strike me as needing evidence to give them more weight.

Ryan Miller

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Re: Super Limits
« Reply #35 on: February 09, 2018, 04:35:26 AM »
Those of us who have put in the hours objectively over decades possibly can develop some ability to sense whether a fleeting detail has some reality. Whilst none of us are infallible in that regard I would consider that Pete is in that experienced category.

Like him I try to give full regard to the hazards involved with fleeting limit-detail. A good part of obtaining and maintaining that critical observing approach comes from dealing with and becoming familiar with less than ideal conditions: the vagaries of seeing in particular. Riding with it when it is less than favourable. Too often I see statements like “ the seeing not that great so I packed it in”; or even “the stars looked agitated tonight so I did not bother opening up”. I have suffered that negativity too but observed anyway and feel that I gained valuable insight/abilities in discernment that I might not have otherwise – and indeed a strengthening of my visual system in that my eyes do not tire easily even now at 70.

Fair enough to point out those hazards, but the ‘explaining away’ surely needs to be tempered to considering other possibilities rather than as proof against, as it often seems to come across.

Visual noise – speaking from experience: it might come as a surprise to some that this can be markedly reduced by practising a lifestyle that favours good circulation; an essential surely for getting optimum vision overall.

As far as visual work goes nowadays I doubt if any of the veterans have delusions of doing great things for science (I never had). Seems to me Pete put across some thoughts that the more practiced might discuss on this Forum beyond being overly reminded of those hazards of which we should be cognisant as observers. Those that do need such instruction perhaps the Beginners Forum more appropriate……..! Other than that we can only hope to set good example and trying not to look like High Priests of Observing – elitism wins no friends nor willing pupils.

DG

Nick Nisianakis

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Re: Super Limits
« Reply #36 on: February 09, 2018, 05:24:24 AM »
I think Brooks is exactly right, but tends to throw the baby out with the bath water. Contrary to professional opinion, not all hobbyists are hacks. If we were, there'd be no point in posting any observations because no one would believe what a fellow hack had to say. We hold to our own experience and interpretation of real limits which differ between observers, anyway. It's entirely possible what one might consider a super limit is really just a normal limit unobserved by the first observer. But because we're both amateur hacks with no professional credibility, we simply believe ourselves if no one else will.

Some of us are right and credibly report what we honestly do see and stick to our guns as often as possible, some of us are probably dead wrong and report imprinted mental images of pictures we've seen. But because we're all amateurs, it's a credibility issue if someone decides it is. We could choose to believe we actually did not see something because someone else said it was impossible, or we could trust our brain did not play a trick on us as some sort of fail safe way to discredit an extreme observation. We should critique our observation and hope someone can repeat it. But we should also consider the possibility we were mistaken. The latter is extremely hard to do when we absolutely know we've seen something and saw it more than once. If it was only a hint of something, it should remain a curiosity.

It's absolutely certain I saw a crater form below the Dawes limit a few times on a single exceptional night, but because I am sticking to my guns I fit the stereotype of a hack who defends his imagination to the bitter end. I am not so certain I saw G and H Trap stars on an equally exceptional night were E and F were bright steady pinpoints. The former is above reproach, the latter remain a curiosity wondering if anyone else has done it in a smaller aperture however impossible it might be. I reported the former with great joy of having achieved it but only mentioned the possibility of latter off line to a friend.

Are there super limits, or simply more flexible real limits that vary with the object type, experience and conditions? I suspect the latter is true, but it's probably also true some folks will consider normal real limits we observe as a super limits beyond their own experience or interpretation. I consider Uranus observations super limits, I cannot do it. But are these observations larger than life or beyond real limits? (Argue elsewhere please, only an example.) I could not tell anyone where an actual limit exists, but it's possible to say it's at least at this point, under these conditions, with this aperture, etc., because I have seen it with my own two lying eyes.

Then I look to theory to see if there is an explanation in well established theory that might prove such an observation is, indeed, possible. I believe in theory, as it pertains to the real world and fortunately near lab like observing conditions, but I wonder if there is another interpretation that explains what I saw and someone else says is probably not likely. Somehow we both have to agree and that common agreement probably needs to contain a valid interpretation of theory we can both share.

inuninab

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Re: Super Limits
« Reply #37 on: February 09, 2018, 09:08:08 AM »
Before we declare what is inadequate aperture for whatever here is a link to an extract from an article based on a talk given by a long-time BAA observer whom I know can be a very severe sceptic.

Some may know that its subject, George Alcock, was steered away from submitting his planetary drawings with his 4” refractor by his ‘betters’ who declared them as over-detailed. In particular none other than W.H. Steavenson “…had stepped in to prevent [their] publication”

http://www.britastro...urnal_item/5752

The full article is members only; but the author later states that the drawings shown in the extract “……bear comparison with the photos of the day taken with the 200-inch………..”

As a footnote to my earlier postand in reference to (BrooksObs):“…..observers going to the eyepiece after repeatedly consulting the details shown on deep printed or on-line images of objects when planning their nightly program. Some will actually bringing such material right to the eyepiece to compare against."...... All I can ask them is why would they want to make their observing experience so shallow. Have they no sense of the joy of the challenge and the elation of honestly eking out subtle detail? Such practices would leave me feeling hollow and time misspent.

DG