The observatory of Juvisy-sur-Orge or Camille Flammarion Observatory is an astronomical observatory founded in 1883 by the French astronomer Camille Flammarion in Juvisy-sur-Orge.
In 1882, Camille Flammarion got this former post house from one of his admirers, Louis-Eugène Meret a rich Bordeaux merchant who died without heir, and he quickly transformed it to an observatory. On the entrance gate, he enrolled the motto "ad veritatem per scientam", i. e. for the truth with science. The observatory was used for more than half a century and observations that were made by Camille Flammarion and astronomers who assisted him made the city Juvisy a center of scientific research until the Second World War. Asteroid 605 Juvisia was named after Juvisy-sur-Orge.
On the obverse of a 74.5 x 58 mm bronze plaque the half right facing portrait of the founder Camille Flammarion is visible. Legend below his name is: "FONDATEUR DE LA SOCIETE ASTRONOMIQUE DE FRANCE", i. e. the founder of the Astronomical Society of France. In front of him the date of issue "MCMXLII", i. e. 1942 is visible. Behind him the sign of medalist "ABEL LA FLEUR - SCULPT -", i. e. Abel Lafleur sculptor (1875-1953).
The reverse shows the observatory's facade among trees. With small capitals below it is its name: "OBSERVATORIE FLAMMARION JUVISY 1863", i. e. Flammarion Observatory Juvisy 1863. On the top two dates 1842 the birth year of Flammarion, and 1942, the issue date of this medal is visible. The legend in seven lines below is: "A CAMILLE FLAMMARION POUR COMMEMORER LE CENTENAIRE DE SA NAISSANCE", i. e. to commemorate the centenary of his birth. Below it on the left the sign producer of this plaque the Paris Mint, on the right the date again "MCMXLII", i. e. 1942 is placed. At at the bottom the motto of entrance gate of the observatory is written "AD VERITATEM PER SCIENTAM", i. e. for the truth with science.