What should I expect to see for Deep space objects through my telescope?

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TahaSiddiqui

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<p>I have a 4.5" Celestron reflector and I am just wondering what galaxies and nebula's would look like through my telescope. I was just out in my backyard&nbsp;last night looking for galaxies. I thought I saw M104 (sombrero galaxy) because it seemed like a thin slice of a star,&nbsp;almost half the size of a regular star. I had suspected it was&nbsp;M104 because first of&nbsp;all,&nbsp;I was looking for&nbsp;it and it also&nbsp;had an edge-on look to it (not a circle)&nbsp;which M104 is. Problem is, it had a yellow color and since i'm pretty sure a 4.5" can't see color on far DSO's,&nbsp;i had some doubt. How should I expect galaxies to look through my telescope? Say if I'm lookin for&nbsp;M81 (6.90 magnitude), what would the size of it be through 50X magnification? Would it just look like a smaller or bigger than stars? Also, the same question with Global Clusters, would these look bigger or smaller than an "average" star? </p><p>Thanks guyss</p>
 
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doubletruncation

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I have a 4.5" Celestron reflector and I am just wondering what galaxies and nebula's would look like through my telescope. I was just out in my backyard&nbsp;last night looking for galaxies. I thought I saw M104 (sombrero galaxy) because it seemed like a thin slice of a star,&nbsp;almost half the size of a regular star. I had suspected it was&nbsp;M104 because first of&nbsp;all,&nbsp;I was looking for&nbsp;it and it also&nbsp;had an edge-on look to it (not a circle)&nbsp;which M104 is. Problem is, it had a yellow color and since i'm pretty sure a 4.5" can't see color on far DSO's,&nbsp;i had some doubt. How should I expect galaxies to look through my telescope? Say if I'm lookin for&nbsp;M81 (6.90 magnitude), what would the size of it be through 50X magnification? Would it just look like a smaller or bigger than stars? Also, the same question with Global Clusters, would these look bigger or smaller than an "average" star? Thanks guyss <br /> Posted by TahaSiddiqui</DIV></p><p>Hi&nbsp; TahaSiddiqui, if your telescope is properly focused and collimated stars shouldn't have any noticeable "size". They should look like pin-points of light. In fact, you should generally use stars to focus your telescope - turn the focuser until the stars don't have any size.&nbsp; Any deep sky object that you can resolve will look bigger than stars. What you will see depends a lot on how bright your night sky is. To estimate your field of view you can use sky and telescope's scope calculator http://www.skyandtelescope.com/observing/objects/javascript/8875112.html or you can measure it yourself by looking at a pair of objects with a known separation. Assuming you have a f/8.7 telescope and are using a 25mm eyepiece with a 50 degree apparent field, your true field of view would be about 1.3 degrees. m81 and m82 are separated by about 3/4 of a degree, so they would both fit comfortably within your field of view (they wouldn't both fit if you upped the magnification to a 10mm eyepiece). You should be able to make out both galaxies without trouble, depending on how bright the sky is you may only be able to really see the bulge of m81 and the general elongated shape of m82 both as fuzzy patches. The bulge of m81 is several arcminutes across, so it should look like a decent sized smudge in your telescope if you look directly at it. If you use averted vision you'll be able to see more details (maybe even spiral arms, depending on the sky).Have you tried looking at globular clusters or bright planetary nebulae yet? I personally think they're better to start with than galaxies because they have higher surface brightnesses, so they're typically easier to find, and easier to make out more details on. Once you become comfortable finding DSOs and using averted vision to observe them, looking for galaxies becomes more rewarding and less frustrating.&nbsp; </p> <div class="Discussion_UserSignature"> </div>
 
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TahaSiddiqui

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Hi&nbsp; TahaSiddiqui, if your telescope is properly focused and collimated stars shouldn't have any noticeable "size". They should look like pin-points of light. In fact, you should generally use stars to focus your telescope - turn the focuser until the stars don't have any size.&nbsp; Any deep sky object that you can resolve will look bigger than stars. What you will see depends a lot on how bright your night sky is. To estimate your field of view you can use sky and telescope's scope calculator http://www.skyandtelescope.com/observing/objects/javascript/8875112.html or you can measure it yourself by looking at a pair of objects with a known separation. Assuming you have a f/8.7 telescope and are using a 25mm eyepiece with a 50 degree apparent field, your true field of view would be about 1.3 degrees. m81 and m82 are separated by about 3/4 of a degree, so they would both fit comfortably within your field of view (they wouldn't both fit if you upped the magnification to a 10mm eyepiece). You should be able to make out both galaxies without trouble, depending on how bright the sky is you may only be able to really see the bulge of m81 and the general elongated shape of m82 both as fuzzy patches. The bulge of m81 is several arcminutes across, so it should look like a decent sized smudge in your telescope if you look directly at it. If you use averted vision you'll be able to see more details (maybe even spiral arms, depending on the sky).Have you tried looking at globular clusters or bright planetary nebulae yet? I personally think they're better to start with than galaxies because they have higher surface brightnesses, so they're typically easier to find, and easier to make out more details on. Once you become comfortable finding DSOs and using averted vision to observe them, looking for galaxies becomes more rewarding and less frustrating.&nbsp; <br />Posted by doubletruncation</DIV></p><p>&nbsp;So you're sayin, in dark skies these galaxies should be easily noticeable and pretty well shaped (through averted vision). I have been looking for Global Clusters but i've had no luck really. I've been lookin for M3 and M13. Global clusters should look like fuzzy unfoused stars am I correct (until you put a higher magnification)? Also, what is a good magnifiaction for them?&nbsp;</p><p>Great advice, thanks man!</p>
 
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MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;So you're sayin, in dark skies these galaxies should be easily noticeable and pretty well shaped (through averted vision). I have been looking for Global Clusters but i've had no luck really. I've been lookin for M3 and M13. Global clusters should look like fuzzy unfoused stars am I correct (until you put a higher magnification)? Also, what is a good magnifiaction for them?&nbsp;Great advice, thanks man! <br />Posted by TahaSiddiqui</DIV><br /><br />If stars don't look like pinpoints (in otherwords if they have any size) you have more serious problems that you need to address first.</p><p>Have you collimated your scope recenty? This is to confirm what doubletruncation said.</p><p>First you need to fix the scope; it will make it possible to tell the difference between a star, a planet, &nbsp;and a galaxy!</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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TahaSiddiqui

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>If stars don't look like pinpoints (in otherwords if they have any size) you have more serious problems that you need to address first.Have you collimated your scope recenty? This is to confirm what doubletruncation said.First you need to fix the scope; it will make it possible to tell the difference between a star, a planet, &nbsp;and a galaxy! <br />Posted by MeteorWayne</DIV><br /><br />Actually it has not been collimated at all (since i've had for about a month). However, I do think it is collimated because when I find a star, and unfocus it, there is a dull&nbsp;circle which is not distorted really at all. When I focus it, it becomes like what you guys are sayin, pinpoints of light. What I meant was that like the size of the point. Ex.&nbsp;Antares is obviously more bigger other the stars from Earth, so it is a bigger point of light through my telescope (compared to ones just near of it). So I'm wondering, galaxies and global clusters should be alot bigger compared to these pinpoints of lights correct (assuming the stars are&nbsp;smaller than Sirius or Antares&nbsp;in my scope)?
 
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doubletruncation

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Actually it has not been collimated at all (since i've had for about a month). However, I do think it is collimated because when I find a star, and unfocus it, there is a dull&nbsp;circle which is not distorted really at all. When I focus it, it becomes like what you guys are sayin, pinpoints of light. What I meant was that like the size of the point. Ex.&nbsp;Antares is obviously more bigger other the stars from Earth, so it is a bigger point of light through my telescope (compared to ones just near of it). So I'm wondering, galaxies and global clusters should be alot bigger compared to these pinpoints of lights correct (assuming the stars are&nbsp;smaller than Sirius or Antares&nbsp;in my scope)? <br /> Posted by TahaSiddiqui</DIV></p><p>As a bit of symantics, it's better to refer to stars as being brighter or fainter when you see them through a telescope rather than bigger or smaller. Assuming you've got your telescope focused and collimated, galaxies and globular clusters generally will look bigger in the area on the sky that they cover than stars. Indeed, anything that you resolve (including a planet) should look bigger than any star that you look at. Depending on the sky, a globular cluster might look either like a cloudy smudge in your field of view, or you may be able to see some individual stars towards the edge of the globular (if you're lucky enough to live somewhere where you can see omega centauri it looks fantastic, you can easily see individual stars away from the core of the cluster even with a small telescope). How big it looks depends on how big it actually is and how far away from us it is, so what you see depends on the object you're looking at. If you up the magnification, a resolved object will look bigger and fainter while an unresolved object (like a star) will look the same (they tend to be somewhat easier to see at higher magnification since the sky looks fainter so you get better contrast).&nbsp; </p> <div class="Discussion_UserSignature"> </div>
 
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TahaSiddiqui

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>As a bit of symantics, it's better to refer to stars as being brighter or fainter when you see them through a telescope rather than bigger or smaller. Assuming you've got your telescope focused and collimated, galaxies and globular clusters generally will look bigger in the area on the sky that they cover than stars. Indeed, anything that you resolve (including a planet) should look bigger than any star that you look at. Depending on the sky, a globular cluster might look either like a cloudy smudge in your field of view, or you may be able to see some individual stars towards the edge of the globular (if you're lucky enough to live somewhere where you can see omega centauri it looks fantastic, you can easily see individual stars away from the core of the cluster even with a small telescope). How big it looks depends on how big it actually is and how far away from us it is, so what you see depends on the object you're looking at. If you up the magnification, a resolved object will look bigger and fainter while an unresolved object (like a star) will look the same (they tend to be somewhat easier to see at higher magnification since the sky looks fainter so you get better contrast).&nbsp; <br />Posted by doubletruncation</DIV><br /><br />Oh sorry, I'll surely refer to&nbsp;stars as brighter or fainter from now on. Thanks for the advice doubletruncation and meteorwayne!
 
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crazyeddie

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I have a 4.5" Celestron reflector and I am just wondering what galaxies and nebula's would look like through my telescope. I was just out in my backyard&nbsp;last night looking for galaxies. I thought I saw M104 (sombrero galaxy) because it seemed like a thin slice of a star,&nbsp;almost half the size of a regular star. I had suspected it was&nbsp;M104 because first of&nbsp;all,&nbsp;I was looking for&nbsp;it and it also&nbsp;had an edge-on look to it (not a circle)&nbsp;which M104 is. Problem is, it had a yellow color and since i'm pretty sure a 4.5" can't see color on far DSO's,&nbsp;i had some doubt. How should I expect galaxies to look through my telescope? Say if I'm lookin for&nbsp;M81 (6.90 magnitude), what would the size of it be through 50X magnification? Would it just look like a smaller or bigger than stars? Also, the same question with Global Clusters, would these look bigger or smaller than an "average" star? Thanks guyss <br /> Posted by TahaSiddiqui</DIV></p><p>To see galaxies in detail, you need a very large scope. &nbsp;In a 4.5" reflector, most will appear as very faint smudges....some round, some oval, some like tiny, faint spindles. &nbsp;Identifying any at all is an accomplishment in such a small instrument.&nbsp;</p> <div class="Discussion_UserSignature"> </div>
 
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