The Astronomical Observatory of the Autonomous Region of the Aosta Valley (OAVdA) and the Planetarium of Lignan are located in Lignan, a mountain village at an altitude of over 1600 a.s.l. in the Saint-Barthélemy valley, about 16 km along the road from the Municipality of Nus.

Opened in 2003, the OAVdA is the only regional astronomical observatory in Italy to have reached a multi-year agreement for research, teaching and educational activities with the INAF, the Italian National Astrophysics Institute. Thanks to the excellent quality of the scientific work carried out, OAVdA researchers are associates of the INAF.

The instruments and resources of the Observatory are among the most impressive in Europe: the Heliophysics Laboratory for observing the sun group with no risk to the eyesight, the Teaching Balcony, with seven 250 mm telescopes in Cassegrain configuration and the Star Theatre for observing the sky with the naked eye, using special laser pointers. The Planetarium takes visitors on a virtual journey through the cosmos, observing planets, constellations, nebulae and galaxies, using computer graphics to discover the most interested physical phenomenon connected with them, thanks to projections created entirely by the staff. Particular attention is also paid to astronomy enthusiasts, who can set up their own instruments in twelve nine-square-metre observation areas, each equipped with power columns for electricity and red LED lighting.

Scientific research
The Observatory works together with other scientific bodies at national and international level, and plays an active part in a number of important research projects:

• Asteroids Project and Corona Project : studying heavenly bodies close to Earth.
• Active Galactic Nuclei Project: monitoring particular galaxies billions of light years away.
• Extrasolar Planets Project: aimed at finding planets in orbit around the other stars in the Milky Way.
• Antarctica Project: dealing with the installation and management of a robotic telescope for infra-red observations.

Significant results obtained at the Observatory include the following: the discovery of a main-belt asteroid, officially christened “Vallée d’Aoste”; participation in the discovery of the two exoplanets of the star XO-2S; the identification of over a hundred variable stars; the observation of an anomalous increase in the emission of energy from the nucleus of the galaxies BL Lacertae and CTA102, phenomena that lasted just a few hours and that during the nights concerned were recorded only at Saint-Barthélemy and at no other astronomical observatory in the world.

Teaching and education: visits.
Alongside research, the astrophysicists devote at least 30% of their time to activities aimed at transmitting their knowledge to schools and to the public.
The initiatives are held exclusively in Italian

• Show at the Planetarium (lasting 1 hour).
  Includes a virtual journey through the cosmos entitled “On the wings of Pegasus”, aimed at families and anyone interested in the sky and in space, dedicated to the sky visible in autumn.

• Night-time guided visit to the Astronomical Observatory (lasting 1.5 hours).
  Includes guided observation of the sky with the naked eye on the Teaching Balcony (depending on the weather conditions).