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  1. Schmidt, Dirk ; Schreiber, Laura ; Vernet, Elise (Ed.)
    An adaptive secondary mirror (ASM) with novel actuator technology is being designed and built for the UH88 telescope as a demonstration of a new generation of ASMs that might be deployed at ground based observatories such as Keck, Subaru, and TMT. Before putting the ASM on the telescope, a set of calibrations and character- izations need to be made in the lab. The crucial lab characterizations of the ASM are to measure its influence functions, and its surface shape when powered and unpowered. To measure these, we develop a novel and inexpensive optical metrology approach using phase measuring deflectometry. This paper describes the simulations we wrote to model the deflectometry method, our data acquisition/analysis pipeline, and a lab prototype sys- tem we built that demonstrates its feasibility on a microelectromechanical systems (MEMS) deformable mirror. Based on the information gained through the deflectometry simulation and the setup prototype, we conclude that phase measuring deflectometry is a reasonable method for obtaining the influence functions but that the absolute surface shape of the ASM will be limited by our knowledge of the placement of components within the deflectometry setup itself. We discuss challenges with extending this approach to larger convex adaptive secondary mirrors. 
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  2. Schmidt, Dirk ; Schreiber, Laura ; Vernet, Elise (Ed.)
    Early adaptive optics (AO) systems were designed with knowledge of a site’s distribution of Fried parameter (r0) and Greenwood time delay (τ0) values. Recent systems have leveraged additional knowledge of the distribution of turbulence with altitude. We present measurements of the atmosphere above Maunakea, Hawaii and how the temporal properties of the turbulence relate to tomographic reconstructions. We combine archival telemetry collected by ‘imaka—a ground layer AO (GLAO) system on the UH88” telescope—with data from the local weather towers, weather forecasting models, and weather balloon launches, to study how frequently one can map a turbulent layer’s wind vector to its altitude. Finally, we present the initial results of designing a new GLAO control system based off of these results, an approach we have named “temporal tomography.” 
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  3. Geometric optical distortion is a significant contributor to the astrometric error budget in large telescopes using adaptive optics. To increase astrometric precision, optical distortion calibration is necessary. We investigate using smartphone Organic Light-Emitting Diode (OLED) screens as astrometric calibrators. Smartphones are low-cost, have stable illumination, and can be quickly reconfigured to probe different spatial frequencies of an optical system’s geometric distortion. In this work, we characterize the astrometric accuracy of a Samsung S20 smartphone, with a view towards providing large format, flexible astrometric calibrators for the next generation of astronomical instruments. We find the placement error of the pixels to be 189[Formula: see text]nm ± 15[Formula: see text]nm Root Mean Square (RMS). At this level of error, milliarcsecond astrometric accuracy can be obtained on modern astronomical instruments. 
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  4. Schmidt, Dirk ; Schreiber, Laura ; Vernet, Elise (Ed.)
    Adaptive Optics (AO) used in ground based observatories can be strengthened in both design and algorithms by a more detailed understanding of the atmosphere they seek to correct. Nowhere is this more true than on Maunakea, where a clearer profile of the atmosphere informs AO system development from the small separations of Extreme AO (ExAO) to the wide field Ground Layer AO (GLAO). Employing telemetry obtained from the ımaka GLAO demonstrator on the University of Hawaii 2.2-meter telescope, we apply a wind profiling method that identifies turbulent layer velocities through spatial-temporal cross correlations of multiple wavefront sensors (WFSs). We compare the derived layer velocities with nearby wind anemometer data and meteorological model predictions of the upper wind speeds and discuss similarities and differences. The strengths and limitations of this profiling method are evaluated through successful recovery of injected, simulated layers into real telemetry. We detail the profilers’ results, including the percentage of data with viable estimates, on four characteristic ımaka observing runs on open loop telemetry throughout both winter and summer targets. We report on how similar layers are to external measures, the confidence of these results, and the potential for future use of this technique on other multi conjugate AO systems. 
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  5. Abstract

    We present stellar rotation periods for late K- and early M-dwarf members of the 4 Gyr old open cluster M67 as calibrators for gyrochronology and tests of stellar spin-down models. Using Gaia EDR3 astrometry for cluster membership and Pan-STARRS (PS1) photometry for binary identification, we build this set of rotation periods from a campaign of monitoring M67 with the Canada–France–Hawaii Telescope’s MegaPrime wide-field imager. We identify 1807 members of M67, of which 294 are candidate single members with significant rotation period detections. Moreover, we fit a polynomial to the period versus color-derived effective temperature sequence observed in our data. We find that the rotation of very cool dwarfs can be explained by simple solid-body spin-down between 2.7 and 4 Gyr. We compare this rotational sequence to the predictions of gyrochronological models and find that the best match is Skumanich-like spin-down,Prott0.62, applied to the sequence of Ruprecht 147. This suggests that, for spectral types K7–M0 with near-solar metallicity, once a star resumes spinning down, a simple Skumanich-like relation is sufficient to describe their rotation evolution, at least through the age of M67. Additionally, for stars in the range M1–M3, our data show that spin-down must have resumed prior to the age of M67, in conflict with the predictions of the latest spin-down models.

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  6. Geyl, Roland ; Navarro, Ramón (Ed.)
    A consortium of industrial and academic partners, coordinated by TNO, is working on the realization of a 620mm adaptive secondary mirror (ASM) for the University of Hawaii’s 2.2-meter telescope. The ASM consists of a 620mm-diameter slumped convex aspherical mirror shell, manipulated by 210 variable-reluctance actuators mounted on a light-weighted support frame. The mirror shell is manufactured to the required accuracy at low cost through slumping. The actuators are driven by dedicated PWM current drivers and commanded through a real-time FPGA-based interface. After successful performance testing of several laboratory prototypes, this project will provide the definitive on-sky demonstration of this new technology. We report on the manufacturing and testing of the major subsystems, and on the integration status of the ASM as a whole. 
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  7. Schmidt, Dirk ; Schreiber, Laura ; Vernet, Elise (Ed.)
    We report on progress at the University of Hawaii on the integration and testing setups for the adaptive secondary mirror (ASM) for the University of Hawaii 2.2-meter telescope on Maunakea, Hawaii. We report on the development of the handling fixtures and alignment tools we will use along with progress on the optical metrology tools we will use for the lab and on-sky testing of the system. 
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  8. Abstract Direct imaging studies have mainly used low-resolution spectroscopy ( R ∼ 20–100) to study the atmospheres of giant exoplanets and brown dwarf companions, but the presence of clouds has often led to degeneracies in the retrieved atmospheric abundances (e.g., carbon-to-oxygen ratio, metallicity). This precludes clear insights into the formation mechanisms of these companions. The Keck Planet Imager and Characterizer (KPIC) uses adaptive optics and single-mode fibers to transport light into NIRSPEC ( R ∼ 35,000 in the K band), and aims to address these challenges with high-resolution spectroscopy. Using an atmospheric retrieval framework based on petitRADTRANS , we analyze the KPIC high-resolution spectrum (2.29–2.49 μ m) and the archival low-resolution spectrum (1–2.2 μ m) of the benchmark brown dwarf HD 4747 B ( m = 67.2 ± 1.8 M Jup , a = 10.0 ± 0.2 au, T eff ≈ 1400 K). We find that our measured C/O and metallicity for the companion from the KPIC high-resolution spectrum agree with those of its host star within 1 σ –2 σ . The retrieved parameters from the K -band high-resolution spectrum are also independent of our choice of cloud model. In contrast, the retrieved parameters from the low-resolution spectrum are highly sensitive to our chosen cloud model. Finally, we detect CO, H 2 O, and CH 4 (volume-mixing ratio of log(CH 4 ) = −4.82 ± 0.23) in this L/T transition companion with the KPIC data. The relative molecular abundances allow us to constrain the degree of chemical disequilibrium in the atmosphere of HD 4747 B, and infer a vertical diffusion coefficient that is at the upper limit predicted from mixing length theory. 
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  10. Evans, Christopher J. ; Bryant, Julia J. ; Motohara, Kentaro (Ed.)
    Since the start of science operations in 1993, the twin 10-meter W. M. Keck Observatory (WMKO) telescopes have continued to maximize their scientific impact and to produce transformative discoveries that keep the observing community on the frontiers of astronomical research. Upgraded capabilities and new instrumentation are provided though collaborative partnerships with Caltech, the University of California, and the University of Hawaii instrument development teams, as well as industry and other organizations. This paper summarizes the performance of recently commissioned infrastructure projects, technology upgrades, and new additions to the suite of observatory instrumentation. We also provide a status of projects currently in design or development phases and, since we keep our eye on the future, summarize projects in exploratory phases that originate from our 2022 strategic plan developed in collaboration with our science community to adapt and respond to evolving science needs. 
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