The Large Binocular Telescope (LBT) is unique in that it is currently the only large telescope (2 x 8.4m primary mirrors) with permanently mounted adaptive secondary mirrors (ASMs). These ASMs have been used for regular observing since early 2010 on the right side and since late 2011 on the left side. They are currently regularly used for seeing-limited observing as well as for selective diffraction-limited observing and are required to be fully operational every observing night. By comparison the other telescopes using ASMs, the Multi Mirrot Telescope (MMT) and more recently Magellan, use fixed secondaries of seeing-limited observing and switch in the ASMs for diffraction-limited observing. We will discuss the night-to-night operational requirements for ASMs specifically for seeing-limited but also for diffraction-limited observations based on the LBT experience. These will include preparation procedures for observing (mirror flattening and resting as examples); hardware failure statistics and how to deal with them such as for the actuators; observing protocols for; and current limitations of use due to the ASM technology such as the minimum elevation limit (25 degrees) and the hysteresis of the gravity-vector induced astigmatism. We will also discuss the impact of ASM maintenance and preparation

Date Published: 26 September 2013
PDF: 10 pages
Proc. SPIE 8860, UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VI, 886014 (26 September 2013); doi: 10.1117/12.2034002

Published in SPIE Proceedings Vol. 8860:
UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VI
Howard A. MacEwen; James B. Breckinridge, Editor(s)