Building the ESO 3.6-metre telescope

The ESO 3.6-metre telescope was commissioned in 1977, and completely upgraded in 1999. In 2004 a new secondary mirror cell was manufactured, improving considerably the image quality of the telescope. In 2007 the control system of the lateral pads was upgraded. The image quality of the telescope is better than 0.2 arcsec at Zenith. The telescope has a horseshoe/fork mounting, and an interchangeable top unit allowing the secondary mirror to be changed from a F/8 to a F/35 Cassegrain focus. The pointing error is about 5 arcsec RMS. The pointing is limited to 70 deg. zenithal distance, and 5.5h HA, but a small region under the pole is reachable. Operation and maintenance of the telescope is the responsibility of ESO.
Since April 2008 HARPS, using the F/8 Cassegrain focus, is the only instrument available at the 3.6m.

The telescope is at a geographical location of 70.7345W, 29.2584S, and an altitude of 2400 metres above sea level.

REOSC, the Optical Department of the SAGEM Group, produces many of the mirrors for ESO's fine telescopes.