Uber-calibration-based Two-level Radial-velocity Zero-point Correction for APOGEE
Abstract
APOGEE delivers high-resolution, near-infrared spectroscopy and highly precise radial velocities (RVs), with extensive repeat observations spanning more than a decade. Long-term RV repeatability is nevertheless limited by instrumental zero-point systematics: exposure-to-exposure drift and fiber-dependent offsets that are only partially tracked by lamp-based wavelength calibration, and that can evolve as fibers are serviced or replaced. We infer and remove these zero points directly from the published per-visit RVs using an uber-calibration framework based on shared repeat observations. We solve sequentially for two sets of minimal calibration units: (plate, night) exposure-level offsets and time-dependent (fiber, observing year) offsets. We apply the method independently to APO and LCO DR17 and to APO DR19. After correction, the same-fiber repeatability within two days reaches a limiting precision of ~14 m/s, and the long-baseline single-visit precision improves by a factor of two from 98.2 to 44.7 m/s. We release per-visit, value-added RV catalogs for DR17 (APO+LCO) and DR19 (APO) containing 3,501,727 visits (3,336,141 fully corrected) of 930,519 unique stars, enabling more reliable RV variability, binary, and Galactic-dynamics studies.
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BibTeX
@misc{zhang2026ubercalibrationbased,
title = {{Uber-calibration-based Two-level Radial-velocity Zero-point Correction for APOGEE}},
author = {Jinming Zhang and Haibo Yuan and Zhijia Tian},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.29012},
eprint = {2609.29012},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.29012},
}
RIS
TY - UNPB
TI - Uber-calibration-based Two-level Radial-velocity Zero-point Correction for APOGEE
AU - Jinming Zhang
AU - Haibo Yuan
AU - Zhijia Tian
PY - 2026
DA - 2026/09/24
PB - arXiv
DO - 10.48550/arxiv.2609.29012
UR - https://arxiv.org/abs/2609.29012
AB - APOGEE delivers high-resolution, near-infrared spectroscopy and highly precise radial velocities (RVs), with extensive repeat observations spanning more than a decade. Long-term RV repeatability is nevertheless limited by instrumental zero-point systematics: exposure-to-exposure drift and fiber-dependent offsets that are only partially tracked by lamp-based wavelength calibration, and that can evolve as fibers are serviced or replaced. We infer and remove these zero points directly from the published per-visit RVs using an uber-calibration framework based on shared repeat observations. We solve sequentially for two sets of minimal calibration units: (plate, night) exposure-level offsets and time-dependent (fiber, observing year) offsets. We apply the method independently to APO and LCO DR17 and to APO DR19. After correction, the same-fiber repeatability within two days reaches a limiting precision of ~14 m/s, and the long-baseline single-visit precision improves by a factor of two from 98.2 to 44.7 m/s. We release per-visit, value-added RV catalogs for DR17 (APO+LCO) and DR19 (APO) containing 3,501,727 visits (3,336,141 fully corrected) of 930,519 unique stars, enabling more reliable RV variability, binary, and Galactic-dynamics studies.
ER -