A New Look at the HI in the Fourth Quadrant
Bibliographic record
Abstract
Using data from the Southern Galactic Plane Survey we have new measurements of the properties of the Milky Way disk in the fourth quadrant, in particular an apparent continuation of the Perseus Arm that extends more than 20 kpc from the Galactic Center. A new generation of HI line and continuum surveys of the Milky Way is underway under the umbrella of the International Galactic Plane Survey (IGPS). These three surveys, the Southern (SGPS, McClure-Griffiths et al. 2001), Canadian (CGPS, Taylor et al. 2003), and VLA (VGPS, Taylor et al. 2002) Surveys, covering longitude ranges 253-357, 65-180, and 18-67 respectively, include combined single dish and interferometer data to achieve resolution approaching 1 with sensitivity to all larger angular scales. The results will allow us to study the HI layer of the Galaxy in unprecedented detail, to map the global properties of the disk such as the midplane position (corrugations), scale height (flare), and large scale features in the surface density such as spiral arms. This paper presents some examples of analysis of the SGPS data to study the outer Galaxy in the fourth quadrant. The left-hand panels of Figure 1 show longitude-velocity diagrams for a few representative latitude ranges; each is an average over several beamwidths, from top to bottom the latitude ranges are +0.35 to +0.45, -0.05 to +0.05, and -0.45 to -0.35. At the heavily degraded resolution and dynamic range of figure 1 the differences among these three l-v diagrams are hard to see, except in the outer Galaxy (positive velocities) where the latitude ranges have spread apart in z by 100 pc or so (distances greater than 15 kpc). The right-hand panels of figure 1 show the latitude moments of the longitudevelocity diagram, i.e. the integrals over the latitude range of the SGPS survey of the brightness temperature weighted by the latitude taken to the power n, as
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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 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.004 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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".