We have recently initiated a multi-institutional research program that will examine existing pipelines and catalog potential sources of variation in their resulting RV measurements. Through a series of EPRV community meetings we aim to establish community recommended, standardized formats for EPRV data products and to develop/distribute the tools necessary for direct comparisons of EPRV data between modern instruments. This program will lay the groundwork for a modular, open source, EPRV analysis toolbox that will be compatible with a wide variety of current and future instruments. Here we will provide a progress report on the program’s steps towards this community-endorsed data standard, and highlight lessons learned from the early years of operation across the NEID, KPF, EXPRES, CARMENES, HPF, and MAROON-X RV spectrographs.
HISPEC (High-resolution Infrared Spectrograph for Exoplanet Characterization) is an infrared (0.98 to 2.46 microns) cross-dispersed, R=100,000 single-mode fiber-fed diffraction-limited echellette spectrograph for the Keck II telescope’s adaptive optics (AO) system. MODHIS (Multi-Objective Diffraction-limited High-resolution Infrared Spectrograph) shares similar specifications as HISPEC while being optimized for TMT’s first-light AO system NFIRAOS. Keck-HISPEC, currently in full-scale development and slated for first light in 2026, and TMTMODHIS, currently in conceptual design phase, will provide increasingly compelling science capabilities from exoplanet atmosphere characterization through both transit and direct high-contrast spectroscopy, to detection and mass measurements through infrared precision radial velocity (RV). The science cases include the precise RV measurements of stars orbiting the Galactic Center, Solar System studies, and the chemodynamical history of nearby dwarf galaxies and the galactic halo.
The latest generation of high-resolution spectrographs on 10m-class telescopes are designed to pursue challenging science cases. Consequently, ever more precise calibration methods are necessary to enable trail-blazing science methodology. We present the High-Resolution Infrared SPectrograph for Exoplanet Characterization (HISPEC) Calibration Unit (CAL), designed to facilitate challenging science cases such as Doppler imaging of exoplanet atmospheres, precision radial velocity, and high-contrast, high-resolution spectroscopy of nearby exoplanets. CAL builds on the heritage of the pathfinder instrument, the Keck Planet Imager and Characterizer (KPIC) and utilizes four near-infrared (NIR) light sources encoded with wavelength information that are coupled into single-mode fibers. They can be used synchronously during science observations or asynchronously during daytime calibrations. A uranium hollow cathode lamp (HCL) and a series of gas cells provide absolute calibration from 0.98 μm to 2.46 μm. Two laser frequency combs (LFC) provide stable, time-independent wavelength information during observation, and CAL implements two low-finesse Fabry-Perot etalons as a complement to the LFCs.
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.
The PAlomar Radial Velocity Instrument (PARVI) is a diffraction-limited, high-resolution spectrograph connected by single-mode fiber to the 200 inch Hale telescope at Palomar Observatory. Here, we present on-sky results for HD 189733 obtained during PARVI’s commissioning phase. We first describe the implementation of our spectral extraction and radial velocity (RV) generation codes. Through RV monitoring, we detect the Rossiter–Mclaughlin signal of the transiting planet HD 189733 b. We further detect the presence of water and carbon monoxide in the atmosphere of HD 189733 b via transmission spectroscopy. This work demonstrates PARVI’s high-resolution spectral capabilities at H band and current intra-night Doppler stability of ∼4 to 10 m s − 1 on an early K dwarf. Finally, we discuss the limitations to this work and ongoing efforts to characterize and improve the Doppler performance of PARVI to the design goal of ∼1 m s − 1 for late-type stars.
KEYWORDS: Sensors, Calibration, Image processing, Spectrographs, Single mode fibers, Point spread functions, Signal to noise ratio, Data acquisition, Absorption, Fiber science
We describe the data reduction pipeline (DRP) for the Palomar Radial Velocity instrument (PARVI). PARVI is a fiber-fed, high-resolution J and H band spectrometer that targets cool, low-mass stars for the purpose of measuring precise radial velocities to determine companion masses. The spectrograph is fed with four single-mode fibers and records science and laser frequency comb wavelength reference spectra simultaneously. We describe and report on the performances of the data reduction process from two-dimensional image acquisition to reduced, wavelength-calibrated one-dimensional spectra. At this time, a single wavelength solution provides a precision of 3.3 m / s.
KEYWORDS: Near infrared, Stars, Single mode fibers, Motion measurement, Frequency combs, Telescopes, Spectroscopy, Spectrographs, Spectral resolution, Signal detection
The field of precision radial velocities (PRVs) aims to detect radial velocity (RV) signals on the order of 1 m/s. The motivation for the push into PRV is to detect the reflex motion of stars induced by Earth-sized orbiting planets. Measuring PRVs in the near-infrared (NIR) provides a number of advantages over optical, such as reduced noise from stellar jitter, and wealth of RV information encoded in the NIR absorption features of cool, low-mass stars. The Palomar Radial Velocity Instrument (PARVI) implements three key strategies to achieve 1 m/s RV precision in the NIR: single-mode fiber (SMF) feeds, thermo-mechanical stabilization of the spectrograph, and a line-referenced, electro-optical modulation frequency comb (LR-EOFC). PARVI is a J & H band (1145-1766 nm) echelle spectrometer with spectral resolution 87,000–121,000. It was installed at the Hale 200" telescope summer 2019, and since then has undergone multiple hardware upgrades to maximize stability. Using the laser frequency comb (LFC) as a light source, we measure a science channel to reference channel stability of 0.001 pixels over the timespan of a single observing night. This measurement includes the motion of 2790 LFC lines over 17 spectral orders in the H band, and corresponds to a radial velocity precision of approximately 1 m/s at the LFC pump line (lambda_p = 1560 nm).
KEYWORDS: Sensors, Signal to noise ratio, Stars, Cameras, Cadmium sulfide, Spectrographs, Single mode fibers, Adaptive optics, Signal detection, Telescopes
A wave of precision radial velocity (RV) instruments will open the door to exploring the populations of companions of low-mass stars. The Palomar Radial Velocity Instrument (PARVI) will be optimized to detect RV signals of cool K and M stars with an instrument precision floor of 30 cm / s. PARVI will operate in the λ = 1.2- to 1.8-μm-wavelength range with a spectral resolution of λ / Δλ ∼ 100,000. It will operate on the Palomar 5.1-m Hale telescope and use Palomar’s PALM-3000 adaptive optics system, single-mode fibers, and an H-band laser frequency comb to probe and characterize the population of planets around cool, red stars. We describe the performance of the PARVI guide camera: a C-RED 2 from First Light Advanced Imagery. The C-RED 2 will be used in a tip-tilt loop, which requires fast readout at low noise levels to eliminate any residual guide errors and ensure the target starlight stays centered on the fiber. At −40 ° C and a frame rate of 400 frames per second in nondestructive read mode, the C-RED 2 has a combined dark and background current of 493 e − / s. Using up-the-ramp sampling, we are able to reduce the read noise to 21.2 e − . With the C-RED 2, PARVI will be able to guide using targets as faint as 14.6 H magnitude.
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