Towards Full-Sky Adaptive Optics with Laser Guide Stars: Overview of the ANU Program on LGS Tip-Tilt

Laser Guide Star Adaptive Optics (LGS AO) has transformed ground-based astronomy by compensating for atmospheric turbulence and enabling near-space-quality resolution. Current systems extend sky coverage of AO–corrected instruments to ∼80%, but full-sky correction remains limited by the tip–tilt indetermination problem. At the Australian National University, we have established a fully funded research program on Laser Guide Star Tip–Tilt (LGS TT), staffed by 3 researchers and 2 PhD students full time, to investigate solutions for this fundamental limitation in next generation Laser Guide Star facilities. The performance of LGS AO systems depends critically on the availability of natural guide stars for tip–tilt measurement. Even under optimistic assumptions (using a magnitude 20 star in the IR), less than 10% of objects at the Galactic pole and less than 80% in the Galactic plane can currently be observed near the diffraction limit. To address this, we are investigating multiple approaches for LGS TT retrieval, leveraging national laser development programs and collaborating with international partners including ESO and ESA. Our efforts target applicability to 8-m class telescopes such as the VLT, with the goal of ultimately enabling diffraction limit across the full sky. During the talk, we will present an overview of the different techniques under investigation and highlight the science cases that could be enabled by this emerging technology.