ESO DOI Service

• Vernet, Elise [European Southern Observatory (ESO)]
• Cirasuolo, Michele [European Southern Observatory (ESO)]
• Pirard, Jean-François [European Southern Observatory (ESO)]
• Cayrel, Marc [European Southern Observatory (ESO)]
• Tamai, Roberto [European Southern Observatory (ESO)]
• Zuluaga Ramírez, Pablo [European Southern Observatory (ESO)]
• Araujo Hauck, Constanza [European Southern Observatory (ESO)]
• Koehler, Bertrand [European Southern Observatory (ESO)]
• Bianca Marchet, Fabio [European Southern Observatory (ESO)]
• Gonzalez, Juan-Carlos [European Southern Observatory (ESO)]
• Tuti, Mauro [European Southern Observatory (ESO)]
• and the ELT team

The Extremely Large Telescope (ELT) is at the core of ESO’s vision to deliver the largest optical and infrared telescope in the world. Following on from our previous Messenger articles we continue with the description of the optical elements of the ELT. In this article we focus on the quintenary mirror (M5), the field stabilisation unit. In combination with the M4 mirror, M5 is vital to delivering the sharp diffraction limited images needed for science by correcting for the vibrations of the telescope, wind shaking and the atmosphere. We describe the main characteristics of the M5, as well as the challenges and complexity of this unique field stabilisation unit and its design and manufacturing status.