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Thread: How do I find the angle between two Galaxies?

  1. #1
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    How do I find the angle between two Galaxies?

    I have two Galaxies I know there RA and Dec how can I find the angle between them by calculation?

    Mark

  2. #2
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    Quote Originally Posted by holmes4 View Post
    I have two Galaxies I know there RA and Dec how can I find the angle between them by calculation?
    Bit of spherical trig that I always need to look up. You can find the slightly complicated equation here.

    Grant Hutchison

  3. #3
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    Nice! There's a decimal degree converter on that page too.
    Thanks!

  4. #4
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    A protractor lol sorry just trying to be funny

  5. #5
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    Quote Originally Posted by Sinbad View Post
    A protractor lol sorry just trying to be funny
    Well, a protractor would be pretty tricky. What you probably meant is a sextant. You could use one, but you have to be able to find the galaxies visually, and you wonít get a very precise measurement, so I think the online version is preferable.


    Sent from my iPhone using Tapatalk
    As above, so below

  6. #6
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    If you want to avoid the math (but, why would you?), at least some--and perhaps most--planetarium programs can do this the easy way. Simply call up the measurement function, select the two galaxies (or any two objects) on screen and you will get the angular separation. Cartes du Ciel (free) and SkyTools3 (not free, and soon to be upgraded) can do this. I didn't try the other programs I have.

  7. #7
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    Quote Originally Posted by holmes4 View Post
    I have two Galaxies I know there RA and Dec how can I find the angle between them by calculation?
    Also, Iím just curious why you (I mean you in general) would want to know that. Is it in order to decide whether you can take a photo of the two galaxies in the same frame?


    Sent from my iPhone using Tapatalk
    As above, so below

  8. #8
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    Quote Originally Posted by Jens View Post
    Also, I’m just curious why you (I mean you in general) would want to know that. Is it in order to decide whether you can take a photo of the two galaxies in the same frame?


    Sent from my iPhone using Tapatalk
    In my case it is just to find the distance between the two galaxies

    For my self this is the viewer that I use legacysurvey.org/viewer?ra=18.8766&dec=-0.8600&layer=decals-dr5&zoom=13

    Mark
    Last edited by holmes4; 2020-Jan-18 at 10:50 AM.

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