The majority of the collection consists of the astronomical glass plates negatives, with most of these being gelatin dry-plate negatives.

Astronomically, the collection consists of both direct image and spectral plates, with two-thirds of the collection made up of the latter. The collection is also mostly known for its widefield imagery and consists of 20% of the known plates ever taken. The glass plates negatives date from the 1870s to the late 1990s. Any given region of the night sky appears on between 500 and 1,000 plates across a