Some photographic plates represent astronomical observations that are always of scientific value: their digitization, a new reduction, and a new analysis provide original and high-precision information for scientific research.
Other plates have a more specific heritage interest: rare plates or plates representing subjects other than the starry sky. Now missing instruments have been photographed on glass plates. Many of these plates deserve to be digitized and made available to the public. In addition to digitization as part of a documentary and heritage policy, a high-definition digitization can reveal details that were passed unnoticed with the prints made at the epoch.
For example, a first description of the plates and heritage prints of the Paris Observatory is available on the Observatory's digital library.
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| Solar eclipse of August 30, 1905, Andoyer mission - Credits Paris Observatory library. | Eye of the great equatorial Coudé of the Paris Observatory by Gaetan Blum (presumed) - Credits Paris Observatory library. |