Prof. León was the founding secretary of the Sociedad Astronómica de Mexico. He was inspired to take action by the appearance of Nova Persei 1901.
Communications from Prof. Luis G. León, Sociedad Astronómica de Mexico, Mexico City, were read at the meeting of the RASC of 12th May 1903, intimating that several of the members of that Society including himself contemplated visiting Canada to observe the eclipse of the Sun in 1905 and asking information as to the best locality for viewing it. The professor also sent several copies of his "Catalogue of Nebulae and Star Clusters" for the library.
At the regular meeting of 23rd June, Prof. Luis G. León, Prof. of Physics in Normal School Mexico and Secretary of the Sociedad Astronómica de Mexico and Mrs. Dolores Gonzáles de León, his wife, graduate of the Normal School of Mexico and member of the Astronomical Society of Mexico, were nominated as honorary associates (without fee) by J.R. Collins and R.F. Stupart.
He wrote to the Society on the 4th October, 1903 on the occasion of the passing of Mr. Lumsden, adding:
My wife and myself are very much obliged to you for our nomination as Honorary members of your Honorable Society. I will do my best in order to write as soon as possible the paper you want for one of the first meetings of 1904.
Prof. León's letter was noted in the minutes of the regular meeting of the 13th instant:
Communications were reported from Dr. Wadsworth of Simcoe and Dr. Marsh of Hamilton, Prof. León of Mexico thanking the Society for electing him an honorary associate of this Society...
The schedule of meetings for April-May-June 1904 included a date for Prof. León's paper 'Solar Activity' to be read at the meeting of 17th May. However, minutes show that the paper presented on that date was given by J.R. Collins, who had been held over for two weeks when his original lecture date on 3rd May was modified to serve as Andrew Elvins' 80th birthday party. (The minutes were incorrect: 4th May 1904 was actually Elvins' 81st birthday.) The León paper was not picked up again when meetings recommenced in the Autumn.
At the meeting of 3rd October, 1904 the secretary read correspondence from Prof. León asking for information respecting the action, if any, to be taken by the Society towards sending a contingent to observe the eclipse of August, 1905. (This eclipse was not to be visible in Mexico; the Canadian expedition to observe it travelled to Labrador, where the event was obscured by clouds; and Prof. León did not participate.)
Another letter from Prof. León was read at the meeting of 16th May, 1905, expressing the regret of the Sociedad Astronómica de Mexico for the death of Mr. Arthur Harvey, and sending fifty copies of his work on the planets in 1905.
The Leóns were noted as "Foreign Members, Honoris Causa" at the very bottom of the list of associates in the Selected Papers and Proceedings of 1902-03, separated from the list of Honorary Fellows and Corresponding Fellows. This tradition was continued in the SP&P of 1904, but the Leóns appeared as honorary associates above the general list of fellows for the first time in the Transactions of 1905.
Prof. León passed away on 23rd April 1913. Senora de León (1880-1969) was listed as a corresponding member for the last time in 1914.