Merging 3 centuries of metadata - experiences from an astronomical scientific letter collection

The 1800s scientific letter collection after Norwegian geophysicist and astronomer Christopher Hansteen (1784-1873) was from the beginning considered to be of great value due to its range and the position of Hansteen as the first astronomer and leading scientist. In the years after Hansteen's death, the collection containing approximately 1500 letters by 420 persons was organized, indexed, and packaged with skill and care, and it survived movings and different types of exploration. In 2005 a project digitized and cataloged approximately half of the letters before funding went out, and the preliminary database was left in the shadows. In 2018 the support for the database ceased, and we transferred the data experimentally to the ExLibris Alma library catalog. Then finally in 2024 - new funding was allocated to finalize the digitization and cataloging, was aligned with the decision to use the "Alvin Platform for digital collections and digitized cultural heritage" for the University of Oslo library special collections. In this presentation, we will explore issues and explain decisions that influence and enable the use and dissemination of these types of fully digitized scientific letter collections. One main observation is that a "one stop solution" does not exist, but if properly documented and preparation for subsequent development is cared for, next century will be grateful.