In 1918 the only Mexican institution dedicated professionally to astronomical work was the National Astronomical Observatory, which had begun operations in 1878. In that year of the 20th century, Mexico was immersed in the armed movement known as the Mexican Revolution, which strongly affected the social and economic structure of the country. The Mexican astronomers saw their group drastically reduced and their infrastructure limited; however, they made great efforts to continue their participation in the international project of the Carte du Ciel, since they were part of the 18 observatories that originally participated in it. Despite the limitations they suffered, they soon joined the group of seven nations that in 1919 formed the IAU, and two members of that observatory actively participated in the first general assembly held in Rome in May 1922.

In this presentation the author narrates some key episodes of his life of serving the IAU for more than seventy years.

Astronomy, more than most sciences, requires an international collaboration. It is the duty of the IAU to insure, between astronomers of the whole world, scientific and human relations. Less than 1,000 astronomers at the time (1946) of my first papers, more than 10,000 today: this means many international collaborations, and many faithful friendships, through several General Assemblies, and many Symposia and Colloquia. To the young astronomers, I must only wish : Cheer up !

Not being able to participate to the XXXth General Assembly in Vienna, the author sent a video presentation (available on the Vienna GA web site), and also provided a spoken text (in French) that was rendered in written form by a voice-to-text software. This text, a recollection of the author’s life “inside the IAU”, was then translated and formatted by Chris Sterken. The English version follows; the original French text is included as an Appendix.

I have written elsewhere from a (mostly) celebratory point of view about early international astronomical projects. This version looks at some of the same projects, but from a less cheerful point of view.

2017 marked the 130th anniversary of the start of the Carte du Ciel project, an ambitious proposal by the Paris Observatory to map the entire sky using photographiy, which required the joint work of numerous observatories in the world. For this endeavour, an impressive organization was designed that included congresses, commissions and publications, which lasted through many years. The Carte du Ciel finally became one of the immediate antecedents of the International Astronomical Union, which in 2019 celebrates its first century. In Latin America, the observatories of Santiago de Chile, La Plata and Rio de Janeiro, the Argentine National Observatory and the Tacubaya Observatory, in Mexico, were involved in the project. In this presentation, we present part of the history of the failures and successes of one of the most important collaborative astronomical projects on the planet.

Benjamin Baillaud was appointed president of the First Executive Committee of the International Astronomical Union which met in Brussels during the Constitutive Assembly of the International Research Council (IRC) on July 28th, 1919. He served in this position until 1922, at the time of the First General Assembly of the IAU which took place in Rome, May 2–10. At that time, Baillaud was director of the Paris Observatory. He had previously been director of the Toulouse Observatory for a period of 30 years and Dean of the School of Sciences of the University of Toulouse. He specialized in celestial mechanics and he was a strong supporter of the “Carte du Ciel” project; he was elected chairman of the permanent international committee of the Carte du Ciel in 1909. He also was the founding president of the Bureau International de l’Heure (BIH) and he was directly involved in the coordination of the ephemerides at an international level. In this paper, we present some of his activities, particularly those concerning international programmes, for which he received international recognition and which eventually led to his election in 1919 to the position of first president of the IAU. We also briefly recount the very first meetings and years of the IAU.

Launched in 1887, the “Carte du Ciel” was an international project aiming at photographing the entirety of the celestial vault. Tasks required for this huge undertaking were divided among 18 observatories around the globe. Instruments were standardized and a series of international conferences established operating modes and prescribed norms to be followed everywhere. In each observatory, however, the drive toward uniformity ran into a variety of minor technical and practical problems. In this paper, we examine the strategies mobilized by observers to tinker with stated rules and adapt them to their own experience as astronomers. To underscore the tension between normative prescriptions and individual practices, we consider the Bulletin of the Permanent International Committee for the execution of the Carte du Ciel as an informal forum where various queries raised and arrangements adopted were shared among the scientific community.