Commanding and Error Recovery of a Binocular Telescope

The Large Binocular Telescope (LBT) consists of two 8.4-meter primary mirrors on a common mount. Each primary is complemented by an adaptive secondary, as well as a tertiary mirror. Since the LBT was designed to perform interferometric measurements, there is a critical need for the ability to control the optics of the two sides of the telescope to high precision. A unique aspect of the LBT is the comparatively large range over which the optics can be adjusted: the optics provide the flexibility for the deliberate acquisition of different targets on each side of the telescope. Designing a Telescope Control System (TCS) which allows for the efficient commanding of both telescope sides viewing the same target (co-pointed), having both telescope sides viewing different targets, and retaining the ability to perform as a single-eyed telescope (monocular mode) is challenging. Error status, particularly in the binocular context, must provide very clear and specific information with respect to the problem in order to enable efficient recovery. This paper describes the high-level flow of the telescope commanding, the binocular observation rules and the recovery strategy for the observer. As the observatory and astronomers gain more experience working within the binocular context, it is anticipated that new strategies may be developed.