ax.plot(azel[20][1], azel[20][0], marker=(2, 0, 0), mew=3, markersize=7)
ax.annotate('Nav 20', xy=(azel[20][1], azel[20][0]), xytext=(azel[20][1], 
    azel[20][0] + 2), horizontalalignment='left', verticalalignment='top')
ax.plot(azel[10][1], azel[10][0], marker=(2, 0, 20), mew=3, markersize=7)
ax.annotate('Nav 10', xy=(azel[10][1], azel[10][0]), xytext=(azel[20][1], 
    azel[20][0] + 2), horizontalalignment='left', verticalalignment='top')
Adding annotation to data points