Photometric determination of asteroid 9 Metis rotation period using the OZT-ALTS robotic telescope
Bibliographic record
Abstract
Asteroid 9 Metis, a prominent main-belt object with an irregular shape and diameter of approximately 190 km, provides insights into early solar system formation and evolution. We determined its synodic rotation period through ground-based photometric observations using the OZT-ALTS robotic telescope at Institut Teknologi Sumatera (Itera). Observations were conducted on May 6, 2025, spanning 6.2 hours continuously. We analyzed 125 calibrated light frames using aperture photometry to construct a light curve. Period analysis employed the Lomb-Scargle periodogram method, suitable for unevenly spaced astronomical data. The periodogram revealed a dominant peak at 2.51 hours. However, the folded light curve exhibited characteristic double-peaked structure with two maxima and minima per cycle, indicating this represents half the actual rotation period. The true synodic rotation period was therefore determined as 5.01 ± 1.01 hours. This result agrees with previously reported values (~5.08 hours), confirming that asteroid 9 Metis has an elongated shape or heterogeneous surface reflectivity. Our study demonstrates that accurate rotational periods can be obtained using moderate-sized telescopes and modern photometric techniques for kilometer-scale asteroids. These findings contribute to understanding asteroid rotational dynamics and provide reference data for future shape modeling studies.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.001 | 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 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".