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We present the current design of WFOS, a wide-field UV/optical (0.31-1.0 µm) imaging spectrograph planned for first-light on the TMT International Observatory 30 m telescope. WFOS is optimized for high sensitivity across the entire optical waveband for low-to-moderate resolution (R ∼ 1500-5000) long-slit and multi-slit spectroscopy of very faint targets over a contiguous field of view of 8′ .3×3 ′ .0 at the f/15 Nasmyth focus of TMT. A key design goal for WFOS is stability and repeatability in all observing modes, made possible by its gravity-invariant opto-mechanical structure, with a vertical rotation axis and all reconfigurable components moving only in planes defined by tiered optical benches parallel to the Nasmyth platform. WFOS’s optics include a linear ADC correcting a 9′ diameter field, including both the science FoV and 4 patrolling acquisition, guiding, and wavefront sensing camera systems; a novel 2-mirror reflective collimator allowing the science FoV to be centered on the telescope optical axis; a dichroic beamsplitter dividing the collimated beam into 2 wavelength-optimized spectrometer channels (blue: 0.31-0.56 µm; red: 0.54-1.04 µm); selectable transmissive dispersers (VPH and/or VBG) with remotely configurable grating tilt (angle of incidence) and camera articulation that enable optimization of diffraction efficiency and wavelength coverage in each channel; all-refractive, wavelength-optimized f/2 spectrograph cameras, and UV/blue and red-optimized detector systems. The predicted instrumental through put of WFOS for spectroscopy averages > 56% over the full 0.31-1 µm range, from the ADC to the detector. When combined with the 30 m TMT aperture, WFOS will realize a factor of ∼20 gain in sensitivity compared to the current state of the art on 8-10 m-class telescopes. 

Lamenting the lack of a natural userland abstraction for preemptive interruption and asynchronous cancellation, we propose lightweight preemptible functions, a mechanism for synchronously performing a function call with a precise timeout that is lightweight, efficient, and composable, all while being portable between programming languages. We present the design of libinger, a library that provides this abstraction, on top of which we build libturquoise, arguably the first general-purpose and backwards-compatible preemptive thread library implemented entirely in userland. Finally, we demonstrate this software stack’s applicability to and performance on the problems of combatting head-of-line blocking and time-based DoS attacks. 

HISPEC is a new, high-resolution near-infrared spectrograph being designed for the W.M. Keck II telescope. By offering single-shot, R 100,000 spectroscopy between 0.98 – 2.5 μm, HISPEC will enable spectroscopy of transiting and non-transiting exoplanets in close orbits, direct high-contrast detection and spectroscopy of spatially separated substellar companions, and exoplanet dynamical mass and orbit measurements using precision radial velocity monitoring calibrated with a suite of state-of-the-art absolute and relative wavelength references. MODHIS is the counterpart to HISPEC for the Thirty Meter Telescope and is being developed in parallel with similar scientific goals. In this proceeding, we provide a brief overview of the current design of both instruments, and the requirements for the two spectrographs as guided by the scientific goals for each. We then outline the current science case for HISPEC and MODHIS, with focuses on the science enabled for exoplanet discovery and characterization. We also provide updated sensitivity curves for both instruments, in terms of both signal-to-noise ratio and predicted radial velocity precision. 

We present the Succinct Range Filter (SuRF), a fast and compact data structure for approximate membership tests. Unlike traditional Bloom filters, SuRF supports both single-key lookups and common range queries: open-range queries, closed-range queries, and range counts. SuRF is based on a new data structure called the Fast Succinct Trie (FST) that matches the point and range query performance of state-of-the-art order-preserving indexes, while consuming only 10 bits per trie node. The false positive rates in SuRF for both point and range queries are tunable to satisfy different application needs. We evaluate SuRF in RocksDB as a replacement for its Bloom filters to reduce I/O by filtering requests before they access on-disk data structures. Our experiments on a 100 GB dataset show that replacing RocksDB's Bloom filters with SuRFs speeds up open-seek (without upper-bound) and closed-seek (with upper-bound) queries by up to 1.5× and 5× with a modest cost on the worst-case (all-missing) point query throughput due to slightly higher false positive rate.