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Photometric Analysis of the Sonneberg Archive Plates

The worldwide number of astronomical photographic plates dating back to the end of the 19th century is estimated to about several millions. The largest German plate archive at Sonneberg Observatory contains about 300000 plates. Digitization of these plates is ongoing. Thus the astronomical heritage of more than 100 years observations of stars becomes more and more accessible.

Example: Photographic Plate from the Sonneberg Archive

Photo plate from Sonneberg archive, Constellation Cygnus, ≈65000 stars
A. Schrimpf
Photo plate from Sonneberg archive, Constellation Cygnus, ≈65000 stars

Photo plate from the Sonneberg archive showing the constellation Cygnus. The plate was taken on 9. June 1986 and shows approximately 65000 stars

Photo plates are non-linear detectors, roughly with a logarithmic sensitivity. The analysis software has to be adapted to the non-linearity. The goals of our research are

  • automatic detection of scratches and marks on the plates
  • detection of transient phenomena by subtraction of adapted artificial data
  • improvement of quality of photometric results from plate data