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Seeing Galaxies

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#26 Tony Flanders

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Posted 08 April 2021 - 05:53 AM

For extended objects like galaxies, a telescope can only make an image appear bigger, never brighter than naked eye.


I wish people would stop saying this! Yes, it is true in an important technical sense -- but that sense is not how most people use the word "bright" in everyday conversation.

 

By this argument, a 100-watt incandescent bulb is no brighter than a 60-watt bulb -- just bigger.

 

If you really feel that you need to make this point -- and it seems quite irrelevant to the original poster's question -- please use the word "surface brightness" rather than just plain "brightness," which has dozens of different technical and non-technical meanings. That will clue the reader that you're making a technical point, and he/she should not be surprised when the statement seems counter-intuitive.

Anyway, in answer to the original poster's question, many objects that appear extremely impressive through telescopes are completely invisible to the unaided eye.

 

The unasked question here is "Do galaxies look impressive in heavily light-polluted skies?" And the answer to that one is "no." They are impressive to the mind when you realize that you are viewing collections of billions of stars lying at unimaginable distances. But to see galaxies in detail -- to see their true beauty -- you need dark skies as well as a telescope.

 

The one exception with respect to needing a telescope is our own Milky Way Galaxy, which is very impressive indeed to the unaided eye from a dark location.


Edited by Tony Flanders, 08 April 2021 - 05:59 AM.

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#27 rob1986

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Posted 08 April 2021 - 06:12 AM

also, check the last paragraph here https://vanderbei.pr...rtureFacts.html

and his statement that for visual use brightness increases with aperture at the same magnification, provided the exit pupilis not larger than [your pupil at the time of observing.], and please note glenns fastidious use of the word contrast, not brightness.

his claim would be accurate if, and this is a huge qualification, the eye were a nicely behaved linear receptor.

It is not.

for illustration. orions skyview pro 8 will reach equal brightness to a 5mm pupil at 36x. at this magnification one would be using a 27.7 mm EP. exit pupil diameter would be 5.6 by our nice ideal equation, but truthfully tht equation assumes things about the eyepeice that I havent been able to find. in reality you exit pupil is created by the ep producing an image of the prime focus into your eye. it wont just produce an image in your eye, but a portion of the prime focus image, which as mentioned has its own defined brightness. this is why different eps can produce different apearant feilds of view at the same magnification. thereafter if the entire exit pupil of the portion of the primefocus image transmits into your eye, below that magnification you will see an increase in brightness.

Edited by rob1986, 08 April 2021 - 06:58 AM.

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#28 Jon Isaacs

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Posted 08 April 2021 - 07:26 AM

your first statement is not true. the brightness ratio depends on how much area the collected light is focused on. if the increase in light collection is more than the magnification then it will brighter.

 

There are two kinds of brightness, total integrated brightness, the sum of all the light collected. This is increased by a telescope. 

 

However, brightness in the context of a galaxy or nebula is normally the intensity or surface brightness.  This is the light per unit area. 

 

Visually, a telescope cannot increase the intensity of an extended object like a galaxy, it can only make it larger, it can also make it dimmer.

 

One has to understand the exit pupil, the light that leaves the eyepiece that enters the eye. The surface brightness of an object is proportional to the area of the exit pupil regardless of aperture, regardless of magnification. If the exit pupil is too large, the light does not enter the eye, this is why a Telescope cannot increase the surface brightness of an extended object.

 

What a Telescope does do is magnify the object so its larger.  A large galaxy like M31 is barely visible unaided despite the fact it's much larger than the moon. This is because of the dimness (low surface brightness), of the object makes it difficult for the eye to detect, the rods have poor resolution.

 

A galaxy that's 3 arc minutes in diameter will be invisible to the naked eye.  It's just too small. 

 

However, if it's magnified by a telescope 100 times, then it will be as nice and big like M31 and it will be visible. 

 

Jon


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#29 Jon Isaacs

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Posted 08 April 2021 - 08:06 AM

 

By this argument, a 100-watt incandescent bulb is no brighter than a 60-watt bulb -- just bigger.

 

And I wish people would stop saying this. Surface brightness is very often how people use the word and it explains why galaxies are difficult to see from an urban site.

 

It's important to understand the concept of surface brightness.

 

The illumination of a 100 watt bulb versus a 20 watt bulb is indeed one of intensity, surface brightness. The reason the room seems brighter with a 100 watt bulb than a 20 watt bulb is that the surfaces of the room are 5 times brighter.

 

This is what surface brightness is.  If you look at a wall, it has a certain brightness. That the surface brightness, the intensity. If you look at 6 square inches or 6 square feet, its equally intense.

 

If you look directly at the bulb and are unable to resolve the filament, this would be analogous to a star and telescopes do make stars brighter.

 

The important concept presented here is the difference between total integrated brightness and intensity or surface brightness.

 

Surface brightness is important in observing galaxies because the surface brightness determines the contrast with the night sky.  The brightness of the night sky is another example of surface brightness. The total integrated brightness of the night sky is huge, far brighter than any star. It's the sum of all the stars and light pollution etc.

 

But it's the intensity or surface brightness of the night sky that we are interested in. It's the contrast between the galaxy and the night sky the eye sees.

 

An urban sky might be 18.0 mpsas, a dark sky, 21.0 mpsas (magnitudes per square arc seconds)  The eye can see with difficulty an object that is about 3 magnitudes dimmer than the background sky.

 

From a urban sky, this would be a surface brightness/intensity of 21.0 mpsas, from a dark sky, 24.0 mpsas.

 

It's the contrast that's important..  Andromeda has a visual brightness of 3.3, if it were a star, it would be easily visible from my backyard. But it's light is spread out over an area of 1 degree x 3 degrees.  It has an average surface brightness of 22.0 mpsas, visible from a dark site,  only the bright core is visible from my backyard. 

 

Very often first time observers look at a galaxy like M101 at magnitude 7.8 or M33 at magnitude 5.8 and think these should be easily seen in a Telescope from an urban backyard.. a magnitude 7.8 star is easily seen in a telescope.

 

They're not.. they're big, they're not intense, they are low surface brightness objects.

 

Jon



#30 rob1986

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Posted 08 April 2021 - 08:29 AM

There are two kinds of brightness, total integrated brightness, the sum of all the light collected. This is increased by a telescope. 

 

However, brightness in the context of a galaxy or nebula is normally the intensity or surface brightness.  This is the light per unit area. 

 

Visually, a telescope cannot increase the intensity of an extended object like a galaxy, it can only make it larger, it can also make it dimmer.

 

One has to understand the exit pupil, the light that leaves the eyepiece that enters the eye. The surface brightness of an object is proportional to the area of the exit pupil regardless of aperture, regardless of magnification. If the exit pupil is too large, the light does not enter the eye, this is why a Telescope cannot increase the surface brightness of an extended object.

 

What a Telescope does do is magnify the object so its larger.  A large galaxy like M31 is barely visible unaided despite the fact it's much larger than the moon. This is because of the dimness (low surface brightness), of the object makes it difficult for the eye to detect, the rods have poor resolution.

 

A galaxy that's 3 arc minutes in diameter will be invisible to the naked eye.  It's just too small. 

 

However, if it's magnified by a telescope 100 times, then it will be as nice and big like M31 and it will be visible. 

 

Jon

as mentioned above, the formula we use for figuring exit pupil is just an approximation that assumes a specific configuration. It can very by as much as 50% and more, depending on the actual optical configuration of the eyepeice. Check the graph in the above Harvard link.

 

Exit pupil is indeed the problem, but it is not intractable,

 

and this does not well explain why the orion nebula, which is a very bright extended object, stands out so clearly in a telescope, but not half as clearly with my naked eye, and I will state that if the lights are shielded from me and I wait half an hour, I see as much of the nebula as I used to see in an 8 inch in the ohio valey region. but I still see it with better contrast, and brighter, in a telescope.


Edited by rob1986, 08 April 2021 - 08:37 AM.


#31 Asbytec

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Posted 08 April 2021 - 08:53 AM

also, check the last paragraph here https://vanderbei.pr...rtureFacts.html

and his statement that for visual use brightness increases with aperture at the same magnification, provided the exit pupilis not larger than [your pupil at the time of observing.], and please note glenns fastidious use of the word contrast, not brightness.

his claim would be accurate if, and this is a huge qualification, the eye were a nicely behaved linear receptor.

It is not.

I'll read your added paragraph more closely. I don't read the last paragraph mentioned the same, paraphrased as focal ratio (photography) doesn't matter. Afocally it doesn't.

Jon hit the contrast topic very well.

I wish I could read the S&T article referenced in the link to see what your driving at. Your previous link on the exit pupil is interesting, but is it significant in practice?

Mel's calculator is pretty cool.
https://www.bbastrod...nCalculator.htm

Edited by Asbytec, 08 April 2021 - 08:58 AM.


#32 Jon Isaacs

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Posted 08 April 2021 - 08:59 AM

as mentioned above, the formula we use for figuring exit pupil is just an approximation that assumes a specific configuration. It can very by as much as 50% and more, depending on the actual optical configuration of the eyepeice. Check the graph in the above Harvard link.

 

 

In general, we use an idealized exit pupil, that is, the telescope and eyepiece are 100% efficient so that surface brightness is indeed proportional to the area of the exit pupil.

 

Of course this not true, this only sets an upper limit to the surface brightness. In relatity, there are transmission losses in the telescope and eyepiece that result in a loss of light.

 

Jon



#33 rob1986

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Posted 08 April 2021 - 09:02 AM

I'll read your added paragraph more closely. I don't read the last paragraph mentioned the same, paraphrased as focal ratio doesn't matter. It doesn't.

Jon hit the contrast topic very well.

I wish I could read the S&T article referenced in the link to see what your driving at. Your previous link on the exit pupil is interesting, but is it significant in practice?

I'll argue more significant in practice than theory.

 

all these short hands are useful, but they're just short hands.

 

the real issue is a combination of relative brightness shifting, magnification, sensitivity thresholds, and all the wonky stuff our eyes can perform when we train ourselves. https://www.baltimor...0025-story.html

 

"In this regime, f-ratio is largely unimportant" is the exact quote.


Edited by rob1986, 08 April 2021 - 09:07 AM.


#34 rob1986

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Posted 08 April 2021 - 09:02 AM

In general, we use an idealized exit pupil, that is, the telescope and eyepiece are 100% efficient so that surface brightness is indeed proportional to the area of the exit pupil.

 

Of course this not true, this only sets an upper limit to the surface brightness. In relatity, there are transmission losses in the telescope and eyepiece that result in a loss of light.

 

Jon

granted



#35 Asbytec

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Posted 08 April 2021 - 09:05 AM

the real issue is a combination of relative brightness shifting...


Going to read your link, but relative brightness shifting sounds like a change in contrast.

#36 Jon Isaacs

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Posted 08 April 2021 - 09:08 AM

just found this

http://adsabs.harvar...JBAA..114...73L

and want to point out, the spread on the graph indicates that the exit pupil formula is only an approximation. and from my calculations the formula itself uses unity as the means for approximating the exit pupil for a given eyepeice.

the actual exit pupil is a complicated computation involving the image size, apparent feild of view, eye relief etc to calculate the actual result. this means that in reality, the number given (16x for an 80mm frak at f11 and a 56 mm ep for instance) is variable and dependent on ep type.

 

You link doesn't work for me.

 

The whole concept of exit pupil is based on optical fundamentals. A passive device cannot increase the amount of light and therefore the surface brightness.

 

Jon


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#37 rob1986

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Posted 08 April 2021 - 09:25 AM

Going to read your link, but relative brightness shifting sounds like a change in contrast.

not on a photometer, but our eyes present light on a logarithmic scale, and was established in before Ptolemy (they thought it was a simple base 2, its closer to 2.5 but this should be sufficient to prove our eyes do not grade brightness based on the inverse square law).

 

this means that our brains are better at perceiving contrast within a certain range. by adjusting that brightness range we can place the unchanged (by inverse square law) brightness within discernible range on a logarithmic scale.


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#38 rob1986

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Posted 08 April 2021 - 09:37 AM

You link doesn't work for me.

 

The whole concept of exit pupil is based on optical fundamentals. A passive device cannot increase the amount of light and therefore the surface brightness.

 

Jon

you aren't changing the amount of light, you are changing where that light is distributed. (ala starting fires with crystal balls.https://www.9news.co... nearby window.



#39 Jon Isaacs

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Posted 08 April 2021 - 09:47 AM

To get back to the original question:

 

What a Telescope does is bring you closer to the galaxy. The vast majority of the galaxies are simply to too small to be seen. 

 

By magnifying the galaxy it's larger, it's big enough for the eye to see.

 

The discussion regarding exit pupil is something of a detour.  In general, galaxies have surface brightnesses that are more than bright enough for the eye to detect, again they're just too small. 

 

In this post, when I write brightness, that means surface brightness.

 

For most smaller galaxies, a 2 mm exit pupil is a good choice, the galaxy is bright enough and the larger magnified size makes it more easily seen. V

 

Contrast of a galaxy or nebula is independent of exit pupil, this is because when you change magnification, both the object and sky darker or brighten equally. Thus contrast is unchanged. Since the eye is primarily a contrast detector,  as long as the object is bright enough, the increase object size is helpful.

 

In general, I recommend swapping eyepieces and determining visually which one provides the best view. For smaller, brighter objects, higher magnifications are generally helpful. For dimmer objects, somewhat lower magnifications brighten the image and can be helpful.

 

A zoom eyepiece is useful because you can play with the magnification in real time and see what's the most effective. 

 

Jon


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#40 Jon Isaacs

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Posted 08 April 2021 - 09:55 AM

you aren't changing the amount of light, you are changing where that light is distributed. 

 

A telescope used visually consists of an objective/mirror and an eyepiece. It has magnification and an exit pupil.

 

This is very different than a single lens focusing at prime focus.

 

And to clarify, when I wrote that a Telescope cannot increase the amount of light, what I meant was a passive device cannot generate light.

 

But yes, the eyepiece does change the way the available light is distributed, increasing the magnification, spreads it out more, decreases the surface brightness, dimming the intensity.

 

Jon



#41 Asbytec

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Posted 08 April 2021 - 09:59 AM

this means that our brains are better at perceiving contrast within a certain range. by adjusting that brightness range we can place the unchanged (by inverse square law) brightness within discernible range on a logarithmic scale.


Yes, that makes sense, and I believe it's also related to spatial frequency (optimum and empty magnification derived from point sources). I haven't finished digesting your earlier link where it seems max resolution in variable lighting conditions is near 3mm exit pupil (for extended contrast). I'm not sure yet how that fits with my experience with galaxies of different parameters as Jon mentioned above. Interestingly Mel's detection calculator gives the same 3nm result for one challenging galaxy I have failed to detect (NGC 660). But I'm not sure it fits for a wide range of other galaxies I've observed.

Edited by Asbytec, 08 April 2021 - 10:03 AM.


#42 Tony Flanders

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Posted 08 April 2021 - 10:35 AM

There are two kinds of brightness, total integrated brightness, the sum of all the light collected. This is increased by a telescope. 
 
However, brightness in the context of a galaxy or nebula is normally the intensity or surface brightness. This is the light per unit area.


For what it's worth, that is not how I normally use the word "brightness" when talking (or thinking) about galaxies. When I carelessly use this word without any qualification, I usually mean the galaxy or nebula's total (integrated) brightness. For me, that is a galaxy's most important attribute. Under dark skies, it is by far the best predictor of a galaxy's visibility in any given instrument. (That's not saying that it's a perfect predictor, mind you -- far from it!)
 
However, since I am aware that people use the word both to mean total brightness and surface brightness, I do my best to avoid using the terms "brightness" and "bright" without qualifiers.

 

For beginners in particular, surface brightness is likely to be a better predictor of galaxy visibility under heavily light-polluted skies. However, total brightness is also extremely important in this case.


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#43 Sketcher

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Posted 08 April 2021 - 11:45 AM

<...snip...>

do telescopes allow me to see better what im already seeing?

<...snip...>

or do telescope allow me to see things my eyes cant catch?

<...snip...>

A telescope does both.  It allows one to better see that which can be seen without using a telescope; and it allows one to see many things that cannot be seen using only one's eyes.

 

Larger (larger aperture) telescopes, all other things being equal, will show more in both scenarios. But it's not at all unusual (actually, it's to be expected) for a smaller telescope to be capable of showing more galaxies and more nebulae when used beneath a darker (far from the effects of artificial lights) sky than a larger telescope will be capable of revealing from a more light-polluted (brighter) sky.  Though in some cases the larger telescope (in the more light-polluted sky) will be able to reveal more detail in some of the galaxies and nebulae.

 

The galaxies M33 and M101 are often invisible to those using sizable telescopes from light-polluted locations.  Yet, both of these galaxies can be (relatively) easily seen from a seriously dark sky with a 1/2-inch telescope -- even if that telescope is a low-quality, singlet refractor.

 

It may be worth pointing out that M33, under a dark enough sky, can be seen with the naked eye.  Yet it can be invisible when observed from light-polluted skies -- even when using a telescope.

 

All of the Messier objects can be easily seen from a dark enough sky (with little to no light-pollution) with an 80mm telescope.  And many of the Messier objects (depending on the criteria and experience of the observer) can be quite impressive with that very same 80mm telescope.

 

In my opinion, any telescope used under a seriously dark sky is going to make a capable deep-sky telescope once the observer has gained sufficient experience.  But under a light-polluted sky, any telescope is far more likely to meet with disappointment -- regardless of the observer's experience.

 

So, for seeing galaxies, one should first of all strive to observe from the darkest skies possible.  Secondly, one should develop one's observing skills -- observing as often as possible with whatever one is able to use.  Thirdly, larger telescopes will show more; but if one has the dark skies and the skills, one might be able to achieve astronomical nirvana with a fairly small telescope.


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#44 AlvinPL

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Posted 08 April 2021 - 12:20 PM

And I wish people would stop saying this. Surface brightness is very often how people use the word and it explains why galaxies are difficult to see from an urban site.

 

It's important to understand the concept of surface brightness.

 

The illumination of a 100 watt bulb versus a 20 watt bulb is indeed one of intensity, surface brightness. The reason the room seems brighter with a 100 watt bulb than a 20 watt bulb is that the surfaces of the room are 5 times brighter.

 

This is what surface brightness is.  If you look at a wall, it has a certain brightness. That the surface brightness, the intensity. If you look at 6 square inches or 6 square feet, its equally intense.

 

If you look directly at the bulb and are unable to resolve the filament, this would be analogous to a star and telescopes do make stars brighter.

 

The important concept presented here is the difference between total integrated brightness and intensity or surface brightness.

 

Surface brightness is important in observing galaxies because the surface brightness determines the contrast with the night sky.  The brightness of the night sky is another example of surface brightness. The total integrated brightness of the night sky is huge, far brighter than any star. It's the sum of all the stars and light pollution etc.

 

But it's the intensity or surface brightness of the night sky that we are interested in. It's the contrast between the galaxy and the night sky the eye sees.

 

An urban sky might be 18.0 mpsas, a dark sky, 21.0 mpsas (magnitudes per square arc seconds)  The eye can see with difficulty an object that is about 3 magnitudes dimmer than the background sky.

 

From a urban sky, this would be a surface brightness/intensity of 21.0 mpsas, from a dark sky, 24.0 mpsas.

 

It's the contrast that's important..  Andromeda has a visual brightness of 3.3, if it were a star, it would be easily visible from my backyard. But it's light is spread out over an area of 1 degree x 3 degrees.  It has an average surface brightness of 22.0 mpsas, visible from a dark site,  only the bright core is visible from my backyard. 

 

Very often first time observers look at a galaxy like M101 at magnitude 7.8 or M33 at magnitude 5.8 and think these should be easily seen in a Telescope from an urban backyard.. a magnitude 7.8 star is easily seen in a telescope.

 

They're not.. they're big, they're not intense, they are low surface brightness objects.

 

Jon

This is great; i think this is a very nice point with amazing examples; this helps me understand what i had in mind when i made the question. Thank you!


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#45 AlvinPL

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Posted 08 April 2021 - 12:21 PM

A telescope does both.  It allows one to better see that which can be seen without using a telescope; and it allows one to see many things that cannot be seen using only one's eyes.

 

Larger (larger aperture) telescopes, all other things being equal, will show more in both scenarios. But it's not at all unusual (actually, it's to be expected) for a smaller telescope to be capable of showing more galaxies and more nebulae when used beneath a darker (far from the effects of artificial lights) sky than a larger telescope will be capable of revealing from a more light-polluted (brighter) sky.  Though in some cases the larger telescope (in the more light-polluted sky) will be able to reveal more detail in some of the galaxies and nebulae.

 

The galaxies M33 and M101 are often invisible to those using sizable telescopes from light-polluted locations.  Yet, both of these galaxies can be (relatively) easily seen from a seriously dark sky with a 1/2-inch telescope -- even if that telescope is a low-quality, singlet refractor.

 

It may be worth pointing out that M33, under a dark enough sky, can be seen with the naked eye.  Yet it can be invisible when observed from light-polluted skies -- even when using a telescope.

 

All of the Messier objects can be easily seen from a dark enough sky (with little to no light-pollution) with an 80mm telescope.  And many of the Messier objects (depending on the criteria and experience of the observer) can be quite impressive with that very same 80mm telescope.

 

In my opinion, any telescope used under a seriously dark sky is going to make a capable deep-sky telescope once the observer has gained sufficient experience.  But under a light-polluted sky, any telescope is far more likely to meet with disappointment -- regardless of the observer's experience.

 

So, for seeing galaxies, one should first of all strive to observe from the darkest skies possible.  Secondly, one should develop one's observing skills -- observing as often as possible with whatever one is able to use.  Thirdly, larger telescopes will show more; but if one has the dark skies and the skills, one might be able to achieve astronomical nirvana with a fairly small telescope.

This is also really good; specially about M33. Thanks!



#46 Dave Mitsky

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Posted 08 April 2021 - 12:41 PM

Here's a list of the Messier galaxies, their integrated visual magnitudes, and their surface brightness figures in magnitudes per square arc minute:
 

M31 3.4 13.6
M32 8.1 12.7
M33 5.7 14.2
M51 8.4 12.6
M58 9.7 13.0
M59 9.6 12.5
M60 8.8 12.8
M61 9.7 13.4
M63 8.6 13.6
M64 8.5 12.4
M65 9.3 12.4
M66 8.9 12.5
M74 9.4 14.4
M77 8.9 13.2
M81 6.9 13.0
M82 8.4 12.8
M83 7.6 13.2
M84 9.1 12.3
M85 9.1 13.0
M86 8.9 13.9
M87 8.6 12.7
M88 9.6 12.6
M89 9.8 12.3
M90 9.5 13.6
M91 10.2 13.3
M94 8.2 13.5
M95 9.7 13.5
M96 9.2 12.9
M98 10.1 13.2
M99 9.9 13.0
M100 9.3 13.0
M101 7.9 14.8
M104 8.0 11.6
M105 9.3 12.1
M106 8.4 13.8
M108 10.0 13.0
M109 9.8 13.5

These figures may vary from source to source.  Taking integrated magnitude and surface brightness into account gives a rough but not perfect guide, due to other variables, of visibility.  The face-on spiral galaxies M33, M74, and M101 have the worst surface brightness figures.


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#47 ButterFly

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Posted 08 April 2021 - 05:21 PM


The whole concept of exit pupil is based on optical fundamentals. A passive device cannot increase the amount of light and therefore the surface brightness.

Very nicely put.  The exit pupil from f/ratio considerations is, afterall, just an approximation.  From an etendue viewpoint, it's a matter of "power out" never exceeding "power in".  The different scope/eyepiece combinations vary in how they affect the distribution of that power.  The "power in" is always object plus background regardless of setup - it's what the setup is pointed at.  The different distribution of "power out" lets us better distinguish the features from the background.

 

Edit: It's worth adding that this "simple" generalization is at the doorstep of information theory, leading to SNR improvements of regions.  Pretty in it's own regard, but my advice for the field is still: swap eyepieces.


Edited by ButterFly, 08 April 2021 - 06:12 PM.

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#48 ButterFly

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Posted 08 April 2021 - 05:42 PM

Taking integrated magnitude and surface brightness into account gives a rough but not perfect guide, due to other variables, of visibility.  The face-on spiral galaxies M33, M74, and M101 have the worst surface brightness figures.

And the object features can very in surface brightness and scale.  M51's spirals are much easier for me.  I have not seen M33's arms in my backyard, even though 604 is plainly visible.

 

Even worse, if those measurement are based on photographs, they pick up much more dim light while pushing out the area.  The stuff that our eyes can see can be much smaller in area - an inherently higher surface brightness region than the whole thing.

 

Many of the brighter nebulae can sustain lots of power at dark sites.  There is lots of detail that just can't be picked up by the eye at lower magnifications.  The North America Nebula has lots and lots little strings and knots.  The information is there at lower powers, but I just can't make sense out of it against the background (neighboring parts of the nebula in this case).
 


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#49 Deep13

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Posted 08 April 2021 - 07:59 PM

Well, this beginner's discussion sure took a trip down the theoretical rabbit hole.

 

Bottom line, you need a telescope to see galaxies.


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#50 Jethro7

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Posted 08 April 2021 - 09:03 PM

Hello Everyone,

Wow!!! This turned out to be a very informative and quite an interesting discussion tonight.

Thank you to the Contributiors here. I stayed out on the sidelines and I feel like I actually  learned  something. 

HAPPY SKIES AND GOOD GALAXY HUNTING Jethro

 

P.S. " Bottom line, you need a telescope to see galaxies"  Thank you Deep13, perfect


Edited by Jethro7, 08 April 2021 - 10:10 PM.

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