Assessing the suitability of H4RG near-infrared detectors for precise Doppler radial velocity measurements

Bechter, Eric B.; Bechter, Andrew; Crepp, Justin R.; Crass, Jonathan

doi:10.1117/1.jatis.5.3.038004

Cited by 6 publications

(4 citation statements)

References 40 publications

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“…Near-infrared spectrographs need to be actively thermally stabilized to a high degree of precision (Becerril et al 2016;Stefansson et al 2016;Challita et al 2018). Furthermore, HgCdTe hybrid near-infrared detectors work differently from optical charge-coupled devices (CCDs; Bechter et al 2019). Last but not least, the calibration procedure requires sources and methods that are adapted to the new wavelength regime (Schäfer & Reiners 2012;Bauer et al 2015;Sarmiento et al 2018;Schäfer et al 2018;Quirrenbach et al 2018).…”

Section: Introductionmentioning

confidence: 99%

The CARMENES search for exoplanets around M dwarfs

Bauer

Zechmeister

Kaminski³

et al. 2020

A&A

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The high-resolution, dual channel, visible and near-infrared spectrograph CARMENES offers exciting opportunities for stellar and exoplanetary research on M dwarfs. In this work we address the challenge of reaching the highest radial velocity precision possible with a complex, actively cooled, cryogenic instrument, such as the near-infrared channel. We describe the performance of the instrument and the work flow used to derive precise Doppler measurements from the spectra. The capability of both CARMENES channels to detect small exoplanets is demonstrated with the example of the nearby M5.0 V star CD Cet (GJ 1057), around which we announce a super-Earth (4.0 ± 0.4 M⊕) companion on a 2.29 d orbit.

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Section: Introductionmentioning

confidence: 99%

The CARMENES search for exoplanets around M dwarfs

Bauer

Zechmeister

Kaminski³

et al. 2020

A&A

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“…Another possibility is the "picture frame effect" seen in some arrays (e.g., Figures 2-3 in the SpeX observing manual 3 ). The picture frame noise is likely to be affected by detector temperature fluctuations at a milli-Kelvin level (Bechter et al 2019). Thus the wave-like variations of the spectral responses can be explained by a slight difference in the detector temperature, similarly to the variations every 16 rows in the upper panel of Figure 7.…”

Section: Pixel-by-pixel Variations Of the Spectral Responsesmentioning

confidence: 89%

Pixel-based Spectral Characterization of Mid-infrared Si Array Detectors for Astronomical Observations in Space

Tsuchikawa

Kaneda

Ishihara

et al. 2020

PASP

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Mid-infrared (IR) array detectors have been used for astronomical observations in space. However, the uniformities of their spectral response curves have not been investigated in detail, the understanding of which is important for spectroscopic observations using large array formats. We characterize the spectral responses of all the pixels in IR array detectors using a Fourier transform infrared spectrometer and cryogenic optics for measurements at high signal-to-noise ratios. We measured the spectral responses of the Si:As impurity band conduction (IBC) array, a flight back-up detector for AKARI/InfraRed Camera. As a result, we find that the Si:As array has intrinsic variations in the spectral response along the row and column directions of the array. We also find that the cutoff wavelength of the Si:As IBC array depends on the intensity of the incident light.

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“…Numerical simulations used to characterize the impact of optical aberrations draw from a foundation of code developed to model the iLocater spectrograph. 11 Used previously to construct an instrument RV error budget, 12 and most recently to quantify uncertainties expected from NIR hybrid array HxRG detectors, 13 this code basis has been augmented to incorporate the effects of wavefront phase errors.…”

Section: Methodsmentioning

confidence: 99%

Studying the Impact of Optical Aberrations on Diffraction-Limited Radial Velocity Instruments

Bechter¹,

Bechter²,

Crepp³

et al. 2021

Preprint

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Spectrographs nominally contain a degree of quasi-static optical aberrations resulting from the quality of manufactured component surfaces, imperfect alignment, design residuals, thermal effects, and other other associated phenomena involved in the design and construction process. Aberrations that change over time can mimic the line centroid motion of a Doppler shift, introducing radial velocity (RV) uncertainty that increases time-series variability. Even when instrument drifts are tracked using a precise wavelength calibration source, barycentric motion of the Earth leads to a wavelength shift of stellar light causing a translation of the spectrum across the focal plane array by many pixels. The wavelength shift allows absorption lines to experience different optical propagation paths and aberrations over observing epochs. We use physical optics propagation simulations to study the impact of aberrations on precise Doppler measurements made by diffraction-limited, high-resolution spectrographs. Using the optical model of the iLocater spectrograph, we quantify the uncertainties that cross-correlation techniques introduce in the presence of aberrations and barycentric RV shifts. We find that aberrations which shift the point-spread-function (PSF) photo-center in the dispersion direction, in particular primary horizontal coma and trefoil, are the most concerning. To maintain aberration-induced RV errors less than 10 cm/s, phase errors for these particular aberrations must be held well below 0.05 waves at the instrument operating wavelength. Our simulations further show that wavelength calibration only partially compensates for instrumental drifts, owing to a behavioural difference between how crosscorrelation techniques handle aberrations between starlight versus calibration light. Identifying subtle physical effects that influence RV errors will help ensure that diffraction-limited planet-finding spectrographs are able to reach their full scientific potential.

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Assessing the suitability of H4RG near-infrared detectors for precise Doppler radial velocity measurements

Cited by 6 publications

References 40 publications

The CARMENES search for exoplanets around M dwarfs

The CARMENES search for exoplanets around M dwarfs

Pixel-based Spectral Characterization of Mid-infrared Si Array Detectors for Astronomical Observations in Space

Studying the Impact of Optical Aberrations on Diffraction-Limited Radial Velocity Instruments

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