Stable Fiber-illumination for Extremely Precise Radial Velocities with NEID

Abstract

NEID is a high-resolution red–optical precision radial velocity (RV) spectrograph recently commissioned at the WIYN 3.5 m telescope at Kitt Peak National Observatory, Arizona, USA. NEID has an extremely stable environmental control system, and spans a wavelength range of 380–930 nm with two observing modes: a High Resolution mode at R ∼ 112,000 for maximum RV precision, and a High Efficiency mode at R ∼ 72,000 for faint targets. In this paper we present a detailed description of the components of NEID’s optical fiber feed, which include the instrument, exposure meter, calibration system, and telescope fibers. Many parts of the optical fiber feed can lead to uncalibratable RV errors, which cannot be corrected for using a stable wavelength reference source. We show how these errors directly cascade down to performance requirements on the fiber feed and the scrambling system. We detail the design, assembly, and testing of each component. Designed and built from the bottom-up with a single-visit instrument precision requirement of 27 cm s−1, close attention is paid to the error contribution from each NEID subsystem. Finally, we include the lab and on-sky tests performed during instrument commissioning to test the illumination stability, and discuss the path to achieving the instrumental stability required to search for a true Earth twin around a solar-type star.

TOI-1670 c, a 40 day Orbital Period Warm Jupiter in a Compact System, Is Well Aligned

“…We observed a transit of TOI-1670 c on UT 2023 April 20 with NEID (Schwab et al 2016) on the WIYN 23 3.5 m telescope at Kitt Peak National Observatory. NEID is a fiberfed (Kanodia et al 2018(Kanodia et al , 2023, ultrastable (Stefansson et al 2016;Robertson et al 2019) spectrograph spanning the 380-930 nm wavelength range with a resolving power of R ∼ 110,000 in its high-resolution mode (Halverson et al 2016). With an exposure time of 1200 s, we obtained 21 spectra over a ∼7 hr span of observations, beginning at airmass = 1.99 and continually rising until observations end at airmass = 1.32.…”

Precise Radial Velocities Using Line Bisectors

“…The RV community has given great attention to the issue of accurate wavelength calibration (Coffinet et al 2019;Zhao et al 2021;Gibson et al 2022;Kanodia et al 2023), whereas in our analysis, we are insensitive to wavelength calibration because the SOLIS/ISS spectra are already shifted to a common reference frame (heliocentric). Nevertheless, our analysis has other limitations.…”