ULTIMATE-START: Current status of the Subaru Tomography Adaptive optics Research experimenT

Abstract

We present the current status of the ULTIMATE-Subaru Tomography Adaptive optics Research experimenT (ULTIMATE-START) project, an upcoming laser tomography adaptive optics (LTAO) system on the Subaru telescope. The main goal of this project is to realize high Strehl ratio AO correction not only in near-infrared bands but also in visible bands above 600 nm. Our LTAO system will be operated with four 32 × 32 Shack Hartmann wavefront sensors (SH-WFSs) and four laser guide stars (LGSs). The LTAO WFSs will be installed behind AO188, which is the current AO system on the Nasmyth platform of the Subaru telescope. We will use the low-order WFS and DM of AO188 for Tip-Tilt measurements with a natural guide star (NGS) and wavefront correction. The DM of AO188 will be upgraded to a 3228 element DM. Assembling of the LTAO WFS system has completed in 2022. Currently WFS data acquisition and tomographic wavefront (WF) estimation testing are underway. We also performed test observations of a prototype single SH-WFS unit with a NGS and LGS with the Subaru telescope. A new laser launching system has been installed. A single LGS is under on-sky performance verification for the open-use observations, and four LGS system, which can make an asterism with 10−40 arcsec diameter, will be installed in 2022. The first light of the entire LTAO system is planned in early 2023. Show more