Characterization of the C-RED 2: a High-Frame Rate Near-Infrared Camera

Characterization of the C-RED 2: a high-frame rate near-infrared camera Rose K. Gibson Rebecca Oppenheimer Christopher T. Matthews Gautam Vasisht Rose K. Gibson, Rebecca Oppenheimer, Christopher T. Matthews, Gautam Vasisht, “Characterization of the C-RED 2: a high-frame rate near-infrared camera,” J. Astron. Telesc. Instrum. Syst. 6(1), 011002 (2019), doi: 10.1117/1.JATIS.6.1.011002. Downloaded From: https://www.spiedigitallibrary.org/journals/Journal-of-Astronomical-Telescopes,-Instruments,-and-Systems on 14 Nov 2019 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use Journal of Astronomical Telescopes, Instruments, and Systems 6(1), 011002 (Jan–Mar 2020) Characterization of the C-RED 2: a high-frame rate near-infrared camera Rose K. Gibson,a,b,* Rebecca Oppenheimer,b Christopher T. Matthews,c and Gautam Vasishtc aColumbia University, Department of Astronomy, New York, New York, United States bAmerican Museum of Natural History, Department of Astrophysics, New York, New York, United States cJet Propulsion Laboratory, California Institute of Technology, Pasadena, California, United States Abstract. 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 ¼ 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. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. [DOI: 10.1117/1.JATIS.6.1.011002] Keywords: exoplanet detection methods; near-infrared instrumentation; precision radial velocity methods; indium gallium arsenide detector characterization. Paper 19061SS received May 31, 2019; accepted for publication Oct. 24, 2019; published online Nov. 15, 2019. 1 Introduction to the much higher mass ratio of the star-planet system. The high ’ The search for exoplanets has captivated astronomers since their mass ratio means that the star is further from the system s bary- discovery in the early 1990s.1,2 With the advent of Kepler, the center and thus has a larger gravitational reflex motion due to the number of confirmed exoplanets increased by orders of magni- presence of the companion. In addition, Sun-like stars are found to have fewer RV jitters in the NIR,11 a pattern that may extend tude and transformed exoplanet studies. While much has been 10,12 done in exoplanet science, the focus for the most part has been to later type stars, with the caveat of starspot dependence. on Sun-like stars. Of the 4057 confirmed exoplanets (as of The Palomar Radial Velocity Instrument (PARVI) is part of a October 6, 2019), 60.1% of those are around G stars, or earlier, next generation of instruments that will shift exoplanet hunting and only 5.3% orbit M stars.3 Cool stars are the most common into the NIR. There are many new precision RV instruments stars in the galaxy4,5 and are expected to host one or more rocky coming online soon; a comprehensive list of new spectrographs 6 can be found in Ref. 13 and those expected to operate beyond planet each, and yet we know the least about their planetary μ systems. 1 m are highlighted in Table 1. PARVI is expected to have One reason for this extreme discrepancy is that the most notably superior instrumental velocity precision, as it uses sin- productive exoplanet missions, such as Kepler and the High gle-mode fibers (SMFs) and a laser frequency comb (LFC) for Accuracy Radial Velocity Planet Searcher (HARPS),7 are best wavelength calibration. suited to observe Sun-like stars. Kepler and its successor, Recently, astronomers have invested in developing methods K2, were sensitive to the 400 to 900 nm wavelength range,8 and to use SMFs in combination with extreme adaptive optics (AO) to enhance ground-based telescope performance.23–25 Extreme HARPS has a similar range of 383 to 690 nm. M stars range 26 from temperatures of 3823 to 2088 K,9 which correspond to AO systems, such as PALM-3000 (P3K), provide diffraction- limited light that can be coupled to small SMFs with Strehl peak wavelength emissions between 758 and 1388 nm. These ∼ cool stars are much dimmer in optical bandwidths compared ratios of 80% in the H band. SMFs provide a number of advan- to Sun-like stars and therefore require significantly more observ- tages over multimode fibers, such as eliminating focal ratio degradation and modal noise, and ensuring a spatially and ing time to achieve a similar signal-to-noise ratio (SNR). To 25 efficiently observe K and M dwarfs, one must go to the near- temporally stable point spread function (PSF). In addition infrared (NIR) where the bulk of their spectral information to providing stable PSFs, SMFs divorce the resolution of a is.10 An advantage of searching for low-mass exoplanet hosts spectrograph from the physical parameters of the telescope. is that it is easier to detect a radial velocity (RV) signal from Instead, the resolving power depends solely on the slit size (fiber low-mass stars due to low-mass planets. This is simply due size) and chosen optics of the spectrograph design. This allows for much smaller spectrographs, which in turn are easier to mechanically and thermally stabilize. ’ *Address all correspondence to Rose K. Gibson, E-mail: rose.gibson@astro. PARVI, to be installed on Palomar s 5.1-m Hale telescope, columbia.edu will produce high-resolution spectra (λ∕Δλ ∼ 100;000) over the Journal of Astronomical Telescopes, Instruments, and Systems 011002-1 Jan–Mar 2020 • Vol. 6(1) Downloaded From: https://www.spiedigitallibrary.org/journals/Journal-of-Astronomical-Telescopes,-Instruments,-and-Systems on 14 Nov 2019 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use Gibson et al.: Characterization of the C-RED 2: a high-frame rate near-infrared camera Table 1 Planned RV instruments operating beyond 1-μ wavelength. Predicted NIR-RV Aperture First Light / instrument Wavelength Instrument Telescope (m) availability precision Spectral resolution reference Reference CARMENES Calar Alto 3.5 01/2016 Facility 1 ms−1 R ¼ 94;600, 80,400 (520 to 960 nm, Etalon Quirrenbach 960 to 1710 nm) stabilized fiber-fed et al.14,15 spectrographs GIARPS TNG 3.6 03/2017 Facility 3 ms−1 R ¼ 115;000, 50,000 (383 to 2450 nm) Th-Ar lamp Claudi et al.16 (HARPS-N + stabilized spectrograph GIANO-B) HPF HET 10.0 11/2017 Facility 1 ms−1 R ¼ 50;000 (818 to 1700 nm) LFC Mahadevan stabilized fiber-fed spectrograph et al.17 iLocator LBT 2 × 8.4 10/2019 PI-only 0.4 ms−1 R ¼ 150;000 to 240,000 (970 to 1300 nm) Etalon Crepp et al.18 stabilized SM fiber-fed spectrograph with full AO correction IRD Subaru 8.2 10/2017 Facility ∼1 ms−1 R ¼ 70;000 or 100,000 (970 to 1750 nm) LFC Kotani et al.19 ceramic component stabilized, partial AO correction, MMF or SMF spectrograph iSHELL IRTF 3.0 10/2016 Facility <10 ms−1 R ¼ ∼75;000, Cassegrain-mounted Gas cell and Rayner et al.20 spectrograph (1100 to 5300 nm) lamp NIRPS La Silla 3.6 08/2019 1 ms−1 R ¼ ∼100;000 (950 to 1800 nm) Lamp and Wildi et al.21 stabilized fiber-fed spectrograph Fabry–Perot with partial (0.4″) AO correction PARVI Palomar 5.1 6/2019 PI 30 cms−1 R ¼ ∼100;000 (1250 to 1800 nm) LFC Internal stabilized SM fiber-fed spectrograph with full extreme AO correction SPIROU CFHT 3.6 03/2018 Facility 1 ms−1 R ¼ ∼70;000 (980 to 2440 nm) Gas cell and Donati et al.22 stabilized fiber-fed spectrograph Fabry–Perot Note: Instruments in bold are those using AO correction and SMFs. For a comprehensive list, see Ref. 13. 1.2-to 1.8-μm-wavelength range. The primary science goal of tests and the expected performance of the C-RED 2 on sky, this instrument is to conduct a 3-year survey of nearby K and given our characterization. M dwarf stars to search for exoplanets and other companions. With an instrument velocity precision floor of 30 cm∕s, we will 2 Instrument Design be able to detect objects less massive than the Earth around K A unique aspect of PARVI is the use of SMFs. Two other spec- and M dwarfs. In addition to the survey, PARVI will be used for trographs are planning on using SMFs in combination with AO: Transiting Exoplanet Survey Satellite candidate follow-up iLocator18 and IRD.19 Traditionally, multimode fibers are used observations and to monitor variability of low-mass stars and for fiber-fed spectrographs, such as SPIROU27 and HARPS,7 brown dwarfs.

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