Modal Noise in High‐Resolution, Fiber‐fed Spectra: A Study and Simple Cure
Why this work is in the frame
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Bibliographic record
Abstract
The transmission modes of a fiber introduce an unstable intensity distribution in high‐resolution spectra which cannot be eliminated by flat‐fielding because the pattern is sensitive to any small changes in fiber position or illumination. These instabilities, rather than photon shot noise, limit the achievable signal‐to‐noise ratio (S/N). In controlled laboratory experiments at a resolution of ∼150,000, we found S/N limited to ≤500 for a range of fiber perturbations and illumination geometries from simple displacement to simulated seeing variations. We find an empirical relation between the number of monochromatic modes and the level of modal noise for which we offer no rigorous explanation. More important, we demonstrate that continuous, low‐amplitude agitation of the fiber close to its output completely eliminates the problem.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 it