Close up of the VISTA telescope

Wide angle view of the VISTA telescope, showing the secondary mirror supporting structure. The VISTA secondary mirror (M2) is 1.24 metres in diameter, while the 4.1-metre primary mirror (M1) is the most highly curved of its size. The extremely high curvature reduces the focal length, making the structure of the telescope very compact. This design enables VISTA to cover a very wide field of view and map large areas of the sky.