Add a beam to a matplotlib plot

To show the beam on an image in matplotlib, use ellipse_to_plot:

>>> from radio_beam import Beam
>>> import astropy.units as u
>>> import matplotlib.pyplot as plt
>>> my_beam = Beam(5*u.arcsec, 3*u.arcsec, 30*u.deg)
>>> ycen_pix, xcen_pix = 15, 15
>>> pixscale = 1 * u.arcsec
>>> ellipse_artist = my_beam.ellipse_to_plot(xcen_pix, ycen_pix, pixscale)
>>> ax = plt.imshow(image)  
>>> _ = ax.add_artist(ellipse_artist)  

The three inputs you need for adding to an arbitrary image are the x and y coordinates to center the beam at in the image, and the pixel scale of the image as defined in the WCS information.