THE START OF THE SAGITTARIUS SPIRAL ARM (SAGITTARIUS ORIGIN) AND THE START OF THE NORMA SPIRAL ARM (NORMA ORIGIN): MODEL-COMPUTED AND OBSERVED ARM TANGENTS AT GALACTIC LONGITUDES −20° < l < +23°
Bibliographic record
Abstract
ABSTRACT Here, we fitted a four-arm spiral model to the more accurate data on global arm pitch angle and arm longitude tangents to get the start of each spiral arm near the galactic nucleus. We find that the tangent to the “start of the Sagittarius” spiral arm (arm middle) is at l = −17° ± 0.°5, while the tangent to the “start of the Norma” spiral arm (arm middle) is at l = +20° ± 0.°5. Earlier, we published a compilation of observations and analysis of the tangent to each spiral arm tracer from longitudes +23° to +340°; in this paper we cover the arm tracers in the remaining longitudes +340 (=−20°) to +23°. Our model arm tangents are confirmed through the recent observed masers data (at the arm's inner edge). Observed arm tracers in the inner Galaxy show an offset from the mid arm; this was also found elsewhere in the Milky Way disk. In addition, we collated the observed tangents to the so-called 3 kpc arm features; statistically they are found to be near l = −18° ± 2° and near l = +21° ± 2°, after excluding misidentified spiral arms. We find that the model-computed arm tangents in the inner Galaxy are spatially coincident with the mean longitude of the observed tangents to the 3 kpc arm features (same galactic longitudes, within the errors). These spatial similarities may be suggestive of a contiguous space.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".