Quirós-Pacheco, Fernando (GMTO), Bouchez, Antonin (GMTO), Conan, Rodolphe (GMTO), McLeod, Brian (Smithsonian Astrophysical Observatory), Schwartz, David (GMTO)
The 25.4m Giant Magellan Telescope (GMT) consists of seven 8.4 m primary mirror (M1) segments with matching segmentation of the Gregorian secondary mirror (M2). When operating the telescope in the diffraction-limited Adaptive Optics (AO) observing modes, the M1-M2 pairs of segments must be phased to a small fraction of the observing wavelength. The first part of this paper presents a revised Phasing / Active Optics control strategy that ensures the phased condition across the scientific field of view, combining measurements of different wavefront sensing channels available in the Acquisition Guiding and Wavefront Sensing (AGWS) system. The second part of this paper presents a preliminary evaluation of the effects of wind buffeting on the phasing performance of the telescope in the LTAO mode. In this observing mode, edge sensors on M1 and M2 sense segment piston disturbances and drive their fast compensation with the Adaptive Secondary Mirror (ASM).
10.26698/AO4ELT5.0145- Proceeding PDF