def equi(map_axis, centerlon, centerlat, radius, color, alpha=1.0):
    """
    This function enables A95 error ellipses to be drawn in cartopy around
    paleomagnetic poles in conjunction with shoot
    (modified from: http://www.geophysique.be/2011/02/20/matplotlib-basemap-tutorial-09-drawing-circles/).
    """
    if not has_cartopy:
        print('-W- cartopy must be installed to run ipmag.equi')
        return
    glon1 = centerlon
    glat1 = centerlat
    X = []
    Y = []
    for azimuth in range(0, 360):
        glon2, glat2, baz = shoot(glon1, glat1, azimuth, radius)
        X.append(glon2)
        Y.append(glat2)
    X.append(X[0])
    Y.append(Y[0])

    plt.plot(X[::-1], Y[::-1], color=color,
             transform=ccrs.Geodetic(), alpha=alpha)