Precise Spectroscopic Radial Velocity Measurements Using Telluric Lines
Bibliographic record
Abstract
Telluric absorption inside our coudé spectrograph is used as a reference spectrum for precise radial velocity measurement. The optical path for this telluric absorption is stable and is not compromised by atmospheric disturbances, such as the jet stream. As an added bonus, the telluric fiducial spectrum is free; i.e., one does not need to construct, regulate, maintain, or suffer throughput losses from a captive‐gas absorption cell. The telluric and stellar spectra span the same portion of the detector and are observed sequentially, but in different diffraction orders. In this way the stellar line profiles are not contaminated by the telluric spectrum and can therefore be used for normal astrophysical line profile analyses, as well as radial velocity studies. However, precise measurements of the temperature and pressure are needed for differential corrections between orders, because the index of refraction of the air in the spectrograph is wavelength dependent. Precision in radial velocity of ∼25 m s −1 is demonstrated.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".