21 research outputs found
Solar Contamination in Extreme-precision Radial-velocity Measurements: Deleterious Effects and Prospects for Mitigation
Solar contamination, due to moonlight and atmospheric scattering of sunlight, can cause systematic errors in stellar radial velocity (RV) measurements that significantly detract from the ~10 cm s−1 sensitivity required for the detection and characterization of terrestrial exoplanets in or near habitable zones of Sun-like stars. The addition of low-level spectral contamination at variable effective velocity offsets introduces systematic noise when measuring velocities using classical mask-based or template-based cross-correlation techniques. Here we present simulations estimating the range of RV measurement error induced by uncorrected scattered sunlight contamination. We explore potential correction techniques, using both simultaneous spectrometer sky fibers and broadband imaging via coherent fiber imaging bundles, that could reliably reduce this source of error to below the photon-noise limit of typical stellar observations. We discuss the limitations of these simulations, the underlying assumptions, and mitigation mechanisms. We also present and discuss the components designed and built into the NEID (NN-EXPLORE Exoplanet Investigations with Doppler spectroscopy) precision RV instrument for the WIYN 3.5 m telescope, to serve as an ongoing resource for the community to explore and evaluate correction techniques. We emphasize that while "bright time" has been traditionally adequate for RV science, the goal of 10 cm s−1 precision on the most interesting exoplanetary systems may necessitate access to darker skies for these next-generation instruments
Solar Contamination in Extreme-precision Radial-velocity Measurements: Deleterious Effects and Prospects for Mitigation
Solar contamination, due to moonlight and atmospheric scattering of sunlight, can cause systematic errors in stellar radial velocity (RV) measurements that significantly detract from the ~10 cm s−1 sensitivity required for the detection and characterization of terrestrial exoplanets in or near habitable zones of Sun-like stars. The addition of low-level spectral contamination at variable effective velocity offsets introduces systematic noise when measuring velocities using classical mask-based or template-based cross-correlation techniques. Here we present simulations estimating the range of RV measurement error induced by uncorrected scattered sunlight contamination. We explore potential correction techniques, using both simultaneous spectrometer sky fibers and broadband imaging via coherent fiber imaging bundles, that could reliably reduce this source of error to below the photon-noise limit of typical stellar observations. We discuss the limitations of these simulations, the underlying assumptions, and mitigation mechanisms. We also present and discuss the components designed and built into the NEID (NN-EXPLORE Exoplanet Investigations with Doppler spectroscopy) precision RV instrument for the WIYN 3.5 m telescope, to serve as an ongoing resource for the community to explore and evaluate correction techniques. We emphasize that while "bright time" has been traditionally adequate for RV science, the goal of 10 cm s−1 precision on the most interesting exoplanetary systems may necessitate access to darker skies for these next-generation instruments
Solar Contamination in Extreme Precision Radial Velocity Measurements: Deleterious Effects and Prospects for Mitigation
Solar contamination, due to moonlight and atmospheric scattering of sunlight,
can cause systematic errors in stellar radial velocity (RV) measurements that
significantly detract from the ~10cm/s sensitivity required for the detection
and characterization of terrestrial exoplanets in or near Habitable Zones of
Sun-like stars. The addition of low-level spectral contamination at variable
effective velocity offsets introduces systematic noise when measuring
velocities using classical mask-based or template-based cross-correlation
techniques. Here we present simulations estimating the range of RV measurement
error induced by uncorrected scattered sunlight contamination. We explore
potential correction techniques, using both simultaneous spectrometer sky
fibers and broadband imaging via coherent fiber imaging bundles, that could
reliably reduce this source of error to below the photon-noise limit of typical
stellar observations. We discuss the limitations of these simulations, the
underlying assumptions, and mitigation mechanisms. We also present and discuss
the components designed and built into the NEID precision RV instrument for the
WIYN 3.5m telescope, to serve as an ongoing resource for the community to
explore and evaluate correction techniques. We emphasize that while "bright
time" has been traditionally adequate for RV science, the goal of 10cm/s
precision on the most interesting exoplanetary systems may necessitate access
to darker skies for these next-generation instruments
Stable fiber-illumination for extremely precise radial velocities with NEID
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 to 930 nm with two
observing modes: a High Resolution (HR) mode at R 112,000 for maximum RV
precision, and a High Efficiency (HE) mode at R 72,000 for faint
targets. In this manuscript 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 , close attention was 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.Comment: Accepted in A
The NEID precision radial velocity spectrometer: Commissioning of the Port Adapter
In October 2019, the NEID instrument (PI Suvrath Mahadevan, PSU) was delivered to the WIYN 3.5 m Telescope at Kitt Peak National Observatory. Commissioning began shortly after delivery, but was paused due to a COVID-19 imposed observatory shutdown in March 2020. The observatory has recently reopened and NEID commissioning has resumed. NEID is an optical (380-930 nm), fiber-fed, precision Doppler radial velocity system developed as part of the NN-EXPLORE partnership. While the spectrometer and calibration system are maintained in a highly controlled environment on the basement level of the WIYN, the NEID Port Adapter mounts directly to a bent-Cassegrain port on the telescope and is responsible for precisely and stably placing target light on the science fibers. Here we present a brief overview of the as-built Port Adapter and its sub-components. We then discuss preliminary on-sky performance compared to requirements as well as next steps as we complete commissioning
Ring resonator in a Sagnac interferometer as a birefringence magnifier
A novel birefringence magnification technique that uses a ring resonator in a Sagnac interferometer is proposed and demonstrated. An enhancement factor of 38 was obtained experimentally. The scheme can be used to increase measurement sensitivity to small birefringence and polarization mode dispersion and to decrease the threshold for nonlinear switching and laser mode locking by a Sagnac interferometer.NRC publication: Ye