One of the major contributors to residual wavefront error for the Adaptive Optics (AO) systems at W. M. Keck Observatory is considered a high order wavefront error. This term accounts for multiple sources including primary mirror segment errors, non-common path aberrations, and more. Fast and Furious (F&F) is a focal plane wavefront sensing algorithm offered as an observation tool to correct these errors. F&F uses a science image and the previous AO correction to measure errors with no diversity frames needed. In practice F&F showed consistent improvement of the Strehl ratio throughout an observing night, with a maximum improvement of 20%. The current observational tool is operational with a single science instrument (NIRC2) and AO with a natural guide star, with upgrades to all AO-fed instruments on the way. This tool can be operated by observers and can be used for monitoring any degradation in AO performance on-sky.
The first scientific observations with adaptive optics (AO) at W. M. Keck Observatory (WMKO) began in 1999. Through 2023, over 1200 refereed science papers have been published using data from the WMKO AO systems. The scientific competitiveness of AO at WMKO has been maintained through a continuous series of AO and instrument upgrades and additions. This tradition continues with AO being a centerpiece of WMKO’s scientific strategic plan for 2035. We will provide an overview of the current and planned AO projects from the context of this strategic plan. The current projects include implementation of new real-time controllers, the KAPA laser tomography system and the HAKA high-order deformable mirror system, the development of multiple advanced wavefront sensing and control techniques, the ORCAS space-based guide star project, and three new AO science instruments. We will also summarize steps toward the future strategic directions which are centered on ground-layer, visible and high-contrast AO.
We report on two critical upgrades to NIRC2, the workhorse diffraction-limited infrared instrument in use with the Keck II telescope Adaptive Optics (AO) system at the W. M. Keck Observatory. NIRC2 has been in operation for over two decades and it is one of the most productive instruments at WMKO. The NIRC2 detector is a 1Kx1K InSb Aladdin-3. We have upgraded the detector electronics from the original system based on transputers to a state-of-the-art Archon controller. One of the most demanded NIRC2 observing modes is high-contrast imaging using Vector Vortex Coronagraphic (VVC) masks, which have been available to the NIRC2 observing community since 2015. To maximize the attenuation of the AO-generated Point Spread Function (PSF) core, the star needs to be precisely centered on the vortex mask over the course of an observation. This is achieved with a servo loop control software based on the Quadrant Analysis of Coronagraphic Images for Tip-tilt Sensing (QACITS) technique. We have migrated the original IDL-based QACITS software to Python, including several updates and a new graphical interface. Both Archon and QACITS upgrades are aimed at boosting the NIRC2 observing efficiency.
We calculate an optical distortion solution for the OSIRIS Imager on the Keck I telescope, by matching observations of globular clusters to a Hubble reference catalogue. This solution can be applied to correct astrometric distortions in OSIRIS frames, improving the astrometric accuracy of observations. We model the distortion with a 5th order Legendre polynomial. The distortion we find matches the expected OSIRIS distortion, and has a fit error of 0.6 mas, but has large residuals of 7 mas. We are currently iterating on an improved reference frame to improve the residual. Additionally, we have installed the Precision Calibration Unit (PCU) on the Keck I optical bench, which will generates an artificial grid of stars for use in future distortion calculations.
We present the status and plans for the Keck All sky Precision Adaptive optics (KAPA) program. KAPA includes (1) an upgrade to the Keck I laser guide star adaptive optics (AO) facility to improve image quality and sky coverage, (2) the inclusion of AO telemetry-based point spread function estimates with all science exposures, (3) four key science programs, and (4) an educational component focused on broadening the participation of women and underrepresented groups in instrumentation. For this conference we focus on the KAPA upgrades since the 2020 SPIE proceedings1 including implementation of a laser asterism generator, wavefront sensor, real-time controller, asterism and turbulence simulators, the laser tomography system itself along with new operations software and science tools, and modifications to an existing near-infrared tip-tilt sensor to support multiple natural guide star and focus measurements. We will also report on the results of daytime and on-sky calibrations and testing.
The Keck All-Sky Precision Adaptive Optics (KAPA) system project will upgrade the Keck I AO system to enable laser tomography with a four laser guide star (LGS) asterism. This paper describes the new infrastructure which is being built for daytime calibration and testing of the KAPA tomographic algorithms.
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