Efficient end-to-end simulations for the TMT NFIRAOS AO system Lianqi Wang (TMT) Abstract Adaptive optics (AO) corrects for the blurring effect of the atmosphere to dramatically improve the image quality of ground-based telescopes, such as the planned Thirty Meter Telscope (TMT). NFIRAOS, the facility AO system for TMT, is a dual conjugate, order 60x60 AO system with 6 laser guide star (LGS) WFS and up to 3 natural guide star (NGS) low order WFS. Such AO systems are so complex that detailed performance analysis can only be done through end-to-end numerical simulations in time domain. The AO simulations at TMT have been carried out using the Multi-threaded Adaptive Optics Simulator (MAOS), freely available at http://github.com/lianqiw/maos. MAOS is written in C and can run on either a CPU or GPU using CUDA technology. MAOS models the complete AO system in time domain, including atmospheric turbulence, telescope pupil obscurations, optics phase errors, physical optics effects in the Shark-Hartmann wavefront sensor (WFS), deformable mirror (DM) influence functions, real time controller (RTC) processing algorithms, etc. With detailed simulations using MAOS, important parameters of the AO system can be determined and/or optimized, such as the order of the WFS, DM stroke requirements, the effects of optics aberrations, tolerances of misalignments, etc. We recently exercised the actual NFIRAOS RTC algorithm in GPU and found that this processor option may be meet the required latency in a few years with rapid advancement of the technology. We also model the sky coverage of the NFIRAOS AO system using time domain simulations with MAOS. The sky coverage metric, as important as it sounds, quantifies the fraction of the sky where the AO system achieves a given level of performance. This is important for LGS AO system because NGS still have to be used to compensate for the tip/tilt/focus uncertainty of LGS. In this talk, I will talk about all these aspects of AO simulations with MAOS.