Over two hundred years of scientific activities are unfolded by the documents held in the historical archives of the Palermo Astronomical Observatory. It was established in 1790 through the will of Ferdinando III, King of Sicilie, and realized by a mathematician from Valtellina, Giuseppe Piazzi (1746-1826), who was its first director.
The long and troubled history of the scientific institution, marked by peaks of excellence, declining phases or just mere survival, depending on the political, economic and cultural conditions and on the astronomers who worked there, could be written thanks to the wealth of information found in the historical archives.
The documents also give witness to the relationships existing between Palermo and various other institutions, such as, the other Italian astronomical observatories, the Italian Astronomical Society, or, at a local level, the Academia de' Regj Studi (now known as the Università di Palermo) and the Real Casa (today, the Sicilian Parliament), the site where the Observatory has always been located.
The administration and account papers represent about one sixth of the entire body of documents. They include the correspondence series, i.e. the official letters sent to and received by the institution. Unfortunately, the letters pertinent to the establishment of the Observatory and its initial years are missing.
The inventory series is made of registers, lists and catalogues of furnishings, instruments and books. The documents have enabled us to trace back the acquisition of almost all the Observatory instruments, now displayed in a permanent exhibition at the "Museo della Specola". The early library catalogues have allowed us to reconstruct the collection of books owned by Giuseppe Piazzi and bequested to the institution.
The records of a scientific nature, produced by research activities, include the series of astronomical observations, which provide data on the position of stars and planets observed with the transit instrument or the equatorial telescope. As an evidence of the work carried out over two centuries, the series is too limited in consistency. Observation registers related to a specific research topic, and thus not embodied by the main series, can be found in the fonds of the astronomers. Unfortunately, Piazzi's observations are missing.
Together with the astronomical observations are the clock testing measurements, a small series comprising data from clock comparison tests.
A good deal of the archival documents relate to meteorology, the discipline in which the institution, from the very beginning of its life, has invested money and efforts. Thereby, playing an important role in its development and maintaining an efficient service for over two centuries. This meteorological archival data make over half of the entire body of documents. The metereological observation registers were compiled both at the main observatory site, i.e. Palazzo Reale, and Villa Valverde, a special site devoted to meteorology, which was en force from 1880 to 1923. The historical archives comprise also the documents relating to the astronomers who worked at the Observatory. The series includes biographical material (education, honors certificates, academic and scientific career), as well as correspondences with peers, sometimes private, publications and astronomical research papers.
A small, peculiar series entitled "Eclipse 1870" consists of the documents relating to the organization of an important national scientific expedition. It was organized by the astronomers Pietro Tacchini and Gaetano Cacciatore, on the occasion of the solar eclipse of 1870.
Presently in custody but not yet available for consultation, are the records related to Giuseppe Vaiana (1935-1991), the scientist who played a major role in the development of X-ray astronomy. This fond will contribute to enriching the quality and extent of the historical archives of the Palermo Astronomical Observatory.