INAF Arcetri Journal

4MOST's First Light

On October 18, 2025, the Multi-Object Spectroscopic Telescope (4MOST), a new and advanced fibre-fed facility for spectroscopic surveys, successfully completed its first sky observations. Installed on the Visible and Infrared Survey Telescope for Astronomy (VISTA), an ESO (European Southern Observatory) telescope in Chile, 4MOST is the largest facility of its kind for observing the southern skies. 

Giuseppe Germano Sacco (INAF Arcetri Astrophysical Observatory) is the Principal Investigator of "The 4MOST Survey of Young Stars" (4SYS), a galactic survey that was selected by ESO among the 15 observing campaigns to be conducted with the 4MOST instrument during its first five years of operation.

The survey will observe approximately 100,000 young stars at a distance of about 1,500 light years, to study the processes that lead to the formation of stars like the Sun and planetary systems similar to ours.

• ESO: https://www.eso.org/sci/publications/announcements/sciann17735.html

• 4MOST: https://www.4most.eu/cms/news/2025/first_light/

• INAF:
  http://www.inaf.it/it/notizie-inaf/prima-luce-4most