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I have the images of a galaxy and the field of view and I would like to determinte the inclination of a galaxy between edge-on and face-on. Would that information be enough to do the calculation? Or what other details would be needed?

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    $\begingroup$ Possibly more than you've provided in this question... Details are required. $\endgroup$ – ProfRob Apr 7 at 22:21
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    $\begingroup$ I have the images of a galaxy and the field of view. Would that be enough to do the calculation? Or what other details would be needed? $\endgroup$ – andi Apr 7 at 23:57
  • $\begingroup$ @andi Welcome to astronomy SE. I included your comment to your question, and as far I as I can tell, it looks like a valid question, so I voted to keep it open. $\endgroup$ – B--rian Apr 8 at 7:11
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If you tilt a circular object, then along one axis the length will appear to be shortened, while along a perpendicular axis the apparent size will be unchanged. So you can use that to determine the tilt angle (inclination).

If we define $0^\circ$ to be face-on, then when tilted at an angle $i$ away from face-on, the shorter axis will appear to be decreased in length by a factor of $\cos i$. Thus, assuming that the galaxy is circular in cross-section, you can determine its inclination from $\cos i = \frac{\rm short\ axis}{\rm long\ axis}$.

This should work for spiral galaxies, but won't work for elliptical galaxies, which aren't necessarily circular in projection when viewed face-on.

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