Resumen
Starting with the paper by G. González and G. González, 1952, BOTT, 1, 5, 1 in the first volume of the Bulletin, various Tonantzintla astronomers worked for years to find the OB stars that delineate the local spiral arms. Perhaps they became discouraged when the 21 cm radio maps appeared, but they should not have been because the optical data produce distances while the radio data measure only radial motions, that need to be interpreted with a model of the motions in our Galaxy. Those motions are more complicated than they thought, so their maps are very inaccurate. The recent 4.5 μm infrared map shows our Galaxy to have a central bar, two major spiral arms, and five small ones.
