The sorting and inventorying of the records relating to the first 150 years of activities at the Institute, that is the period between the 19th century and the first half of the 20th centruy, took place between 1993 and the beginning of 1998. Altogether, this large body of documents occupy 20 linear meters of shelving.
Early on, the materials including the oldest records (dating back to the moment in which the location of the Observatory was transferred from the Palace of the Science Academy to Palazzo Madama) were held, without any order, inside large cardboard boxes, in the Observatory cellar. In the absence of inventories or indexes which might reflect previous classifications, it was necessary to survey all of the documents so as to obtain a detailed view of the contents, and, accordingly, group the records into homogenous series.
Due to the absence of previous interventions (with the exception of a small portion of the oldest records, which were sorted during the first years of the 20th century), the classification criteria selected had to be, in large part, original. Although defined retrospectively, the organization of the archival series has, nevertheless, intended to preserve in its structure sufficient flexibility so as to respect any evidence of previous interventions in case they emege during the course of the reorganization works.
A second phase of the reorganization work, carried out from 2005 to 2007, has dealt with more recent records, spanning from the second post-war period to 1986, the year which marks the end of the studies in classical astronomy for the Observatory and the start of Professor Attilio Ferrari's directorship.
The second batch of records are also known as "Deposit archives" - as opposed to the first batch of documents which are called the "Historical-Scientific archives". This second batch, being more extensive than the first, occupies about 30 linear meters of shelving. In fact, the label "Deposit archives" is not entirely correct, as this series includes both records which should pertain to the historical section and records which are less than 40 years old. In some cases, it has been necessary to extend the chronological limit set in the previous sorting phase (which was 1986), so as to include more recent materials which were at high risk of being dispersed. The work has allowed the addition to the first batch of records some archival units which, based on logical and chronological criteria, found their correct place inside previously defined archival series.