The Institut d'Astrophysique Spatiale in Orsay

The Ψ2 program "The Milky Way in the age of Gaia" is hosted by the Institut d'Astrophysique Spatiale located on the Paris-Sud University campus in the town of Orsay, about 25 km south-west of Paris.

The Orsay campus is conveniently connected to the city center, to the two Paris airports (Charles de Gaulle and Orly) and to two major train stations (Gare du Nord and Massy TGV) through the RER B, one of the lines of the Paris area local train system (RER - Réseau Express Régional).

The Orsay campus can be reached from Chatelet (center of Paris) in 35 minutes.

What transport ticket to buy ?

For the commuting, we advise you to buy a Navigo pass, which you could already purchase upon arriving the airport. Unfortunately we cannot reimburse these Navigo passes or other ways of commuting fares.

Getting on the Paris RER-B line

  • By air
    • Charles de Gaulle airport. Connected to RER-B line
    • Orly airport. Take the Orlyval light rail line to Antony (on the RER B line).
  • By train
    • Gare du Nord (Eurostar, Thalys). Connected to RER-B line.
    • Gare de l'Est, Gare Saint-Lazare, Gare Montparnasse, Gare d'Austerlitz. Take the subway to reach the RER B line. See RATP.
    • Massy TGV train station. Connected to the RER B line.
  • By subway
    In the city center, the RER is interconnected with the subway system (look here if you dare !). The two systems can be combined with a single ticket.

Reaching the Institut d'Astrophysique Spatiale

  • Once on the RER-B, take a train that terminates at Saint-Rémy-les-Chevreuse. Check the electronic boards on the RER plateform.
  • Get off at Orsay-ville station.
  • Walk to IAS (8 min walk) :
More maps here