Quirós-Pacheco, FernandoFernandoQuirós-Pachecovan Dam, MarcosMarcosvan DamBouchez, Antonin H.Antonin H.BouchezConan, RodolpheRodolpheConanHaffert, Sebastiaan Y.Sebastiaan Y.HaffertAGAPITO, GuidoGuidoAGAPITODemers, RichardRichardDemers2025-03-072025-03-0720229781510653511http://hdl.handle.net/20.500.12386/36529The Natural Guidestar Adaptive Optics (NGAO) system of the Giant Magellan Telescope (GMT) uses a visible-light modulated pyramid wavefront sensor (PWFS) to measure the wavefront aberrations, including residual segment piston errors. This paper presents an updated wavefront sensing and control architecture that increases the robustness of segment piston control. In the first place, the Natural Guide star Wavefront Sensor (NGWS) design has been updated to incorporate the recently proposed Holographic Dispersed Fringe Sensor (HDFS) as a second wavefront sensing channel measuring unambiguously differential segment piston errors as large as ~14 microns. In the second place, an optimized modal control strategy has been developed to compensate mode-by-mode for the optical gain of the PWFS. We report on the simulated NGAO performance results obtained when using a R=12 guide star, and with a turbulence strength of r0 =12.8 cm.STAMPAenConference paper10.1117/12.26296182-s2.0-85175875527https://www.spiedigitallibrary.org/conference-proceedings-of-spie/12185/2629618/The-Giant-Magellan-Telescope-natural-guidestar-adaptive-optics-mode/10.1117/12.2629618.fullhttps://api.elsevier.com/content/abstract/scopus_id/85175875527FIS/05 - ASTRONOMIA E ASTROFISICA