Angular Resolution of a Telescope

[Michael E. Marotta]

Angular resolution in radians = 1.22 times the quotient (wavelength / aperture) 

Make sure to keep the units the same, wavelength may be in angstroms; aperture may in inches. So, do the conversions first.

For example, a telescope with a 10-inch lens is assumed to be observing in the visible spectrum. Assume the middle range. The last step is to convert radians to arc seconds.

Answer: 0.54 arc seconds.

My telescope has an aperture of 102 mm.

Answer ranges 0.98″ (violet) to 1.72″ (red)

Attachments:

1. 

   Notebook-for-FK-pg-119-2.jpeg
   

[Michael E. Marotta]

The example comes from  A Student’s Guide to the Mathematics of Astronomy by Fleisch & Kregenow, Cambridge University Press, 2013.

[Dr Paul Leyland]

You give the accurate (and correct) procedure.  For a decent approximation I just divide 140 by the aperture in mm, which gives an answer which is “good enough”.  In your case 140/102 = 1.37.

Easy to remember.

[Author]

Posts