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A Look At Astronomy...


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#1 Adam Nagy

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Posted 27 December 2008 - 11:35 AM

Hi Everyone,

I've been wanting to start this thread for quite some time. A.Sphere and I have been chatting and I gave him a question that will give him an opportunity to display some really cool pictures and some informative information.

A.Sphere is an astronomer (so he says ;) ) but from what I've read from him he does seem pretty well informed on modern day astronomy.

What I would like to do here is compare what astronomers actually see verses filtered images and through to enhanced images.

I would like to see how they compare optical images to radio images and at what point some artistic freedom is used to enhance these images.

I would like to avoid discussion about the Big Bang and Origins but focus on the hard results of peering into space and the methods used for calculating certain knowledge.

We have a great opportunity to let an astronomer answer some questions about basic astronomy so don't screw it up with sarcasm and looking for a chance to pounce on him for a debate. (I'm the key focus of this exhortation. I was looking in a mirror when I wrote it. :o )

This could be a fun lesson for all of us.

Some topics that I personally would like to here about are:

Parallax Trigonometry
Red Shift Observations (Facts & Assumptions)
Optical results and image enhancement

A.Sphere, when you're ready take-er-away and hopefully this can be a fun informative thread with lots of cool pictures. :)

#2 Adam Nagy

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Posted 27 December 2008 - 08:59 PM

With A.Sphere's permission, I'm posting a short correspondence that A.Sphere and I had regarding my inquiry.

Hey A.Sphere,

I was wondering if you could help me out.

This is right up your ally. I would like to know how to get access to images that are actually representative of what we look at in space. You know as well as I do that most images are doctored to enhance clarity.

Also, when we look at super nova are they all in the Milky Way? You know the ones that are sharp like eagle nebula and crab nebula? Can you get me un-doctored images of these? If we've identified them in other galaxies what is the best resolution image you can offer me?



There not really doctored. They are false colored images. This means that filters were used to sometimes to better see some sort of physical process. Much of the light from these astronomical objects are outside the visible wavelength and filters allow us to see them (kind of like night vision allows us to see infrared). Here is a link about it from Chandra's website:

http://chandra.harva...alse_color.html

Many of these nebula show up as black and white when you view them through telescopes and binoculars. For example, if you have a nice pair of binoculars and you go out on a clear night and aim them at the second star in Orion's sword down from his belt you will see something like this:

Posted Image

A telescope will provide you with better viewing of course. Typically filters are used to take separate images in various colors and then the images are merged into one image. For example, this pic of the ring nebula was taken by merging three color images captured using filters:

Posted Image

If you have a 12 inch Schmidt Cassengrain scope it will look just like that but in gray scale . When you do this its a true color image.

So the two types are False-Color and True-Color. The true color ones you can see with aid from binoculars or a telescope but the false-color ones are in wavelengths that we cannot always see. If you Google "true color nebula" you will get some hits. Much of what we see in space is also faint color so to really see it well you would need a 12 inch scope and a ccd camera so you can do long exposure times (the human eye can't integrate faint light for than a few hundredths of a second

Here are some true color amateur astronomy images:

http://www.aip.de/~m...ageGallery.html

Here is another amateur astronomy gallery without filters at all:

http://www.mv.com/users/wje/astro.html

You cannot see the nebula in other galaxies because that kind of resolution doesn't exist.

I actually recommend getting a 12 inch SC scope and doing astrophotography. I use to teach astronomy lab and I had access to 12 inch scopes and ccd cameras and I could plug up my laptop and gaze at the cosmos all night. It is humbling to see the images in a more purist form than Hubble gives. Now that I don't have access I am saving up to buy the equipment myself. In all it runs about $2000 dollars to get a decent set.



#3 Adam Nagy

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Posted 27 December 2008 - 09:07 PM

I can see that using the language "doctored up" was inflammatory and I also apologize for the implications. I would like to know what image filters produce. Are these simply shaded lens that filter out certain colors? When false color images are imposed on each other who and how do they decide what colors to leave where?

For instance if crab nebula looks like this after enhancement...

Posted Image

...what are the original images and how do they go about imposing false color images and what does the enhancement process involve?

On a side. Where is the crab nebula located? I hope I'm not asking a stupid question but I presume that images like this could only be obtained in our galaxy, is this correct?

Adam

#4 falcone

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Posted 28 December 2008 - 05:51 AM

The Crab Nebula is in the constellation Taurus which you can see in the northern hemisphere in winter. It's part of our galaxy, yes.

Nebulae such as the Crab are understood to be the remenants of supernovae, and the location of the Crab corresponds with observations of a supernova made by Chinese astronomers in the 11th century. You get stuff like this on wiki.

Supernovae have been detected much further away though - 10 billion light years is the farthest I've read about. That's way outside our galaxy.

A cool piece of free software I found a while ago is Worldwide Telescope. It's great for general orientation and has loads of stunning images

#5 Adam Nagy

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Posted 28 December 2008 - 06:30 AM

Supernovae have been detected much further away though - 10 billion light years is the farthest I've read about. That's way outside our galaxy.

A cool piece of free software I found a while ago is Worldwide Telescope. It's great for general orientation and has loads of stunning images

View Post


I downloaded "Worldwide Telescope" and Wow! Googleearth has a similar feature but it looks like you can get lost on this one a little easier. Thanks falcone!

What are the best un-enhanced images of novae in other galaxies?




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