[Python] How to scatter plot marker size based on astronomy image data?

For example, in this code I plot a astronomy FITS image:

def displayimage(img, wcs):
fig, ax = plt.subplots(
figsize=(5, 3), layout="compressed", subplot_kw={"projection": wcs.celestial}
)
norm = simple_norm(img, vmin=0, vmax=np.nanmax(img.value), stretch="linear")
im = ax.imshow(img, norm=norm, cmap="viridis", origin="lower")
lon = ax.coords[0]
lat = ax.coords[1]
lon.set_axislabel("RA")
lat.set_axislabel("Dec")
plt.colorbar(im)
plt.show()

displayimage(cube)


Now I want to scatter some hollow circles based on coordinates and size such as:

(RA, Dec, Size) = (120*u.deg, 30*u.deg, 25*u.arcmin)


how to calculate the s value in matplotlib.pyplot.scatter(x, y, s) so that the size of circles matches the data?

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