The Large Binocular Telescope: binocular all the time

Abstract

The Large Binocular Telescope Observatory is a collaboration between institutions in Arizona, Germany, Italy, Indiana, Minnesota, Ohio and Virginia. The telescope uses two 8.4-m diameter primary mirrors mounted sideby- side on the same AZ-EL mount to produce a collecting area equivalent to an 11.8-meter aperture. Many science observations collect the light from the two sides separately. With the arrival of the second copy of the near-infrared spectrometer and the second copy of the optical spectrometer, the telescope is observing with both apertures a significant fraction of the time. The light from the two primary mirrors can be combined to produce phased-array imaging of an extended field. This coherent imaging along with adaptive optics gives the telescope the diffraction-limited resolution of a 22.65-meter telescope. Adaptive optics loops are routinely closed with natural stars on both sides of the telescope for combined beam observations. Twin laser guide star constellations have recently been installed for ground layer adaptive optics observations. Commissioning of new instruments and focal stations for high resolution spectroscopy and near-infrared phased-array imaging is underway.