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Planet articles against the computed sky — Venus elongation and 犯 separations
(1) Distribution of Venus's elongation on 'Venus seen by day' dates per source against random dates. (2) For '月犯X / X犯Y' articles whose two bodies are in the name dictionary, the minimum angular separation that night.
On 'Venus seen by day' dates the planet's elongation has a median near 43° in all three sources against 31° on random dates, and for the '月犯X / X犯Y' pairs (Goryeosa 454 pairs: 285 Moon, 169 planet) the minimum separation that night has a median of 2.8° (2.2° with a ±1-day window) against 91° at random. Only about four in ten fall within 1.5°, so 犯 should not be read as a modern close approach.
- Formula
- (1) Median elongation at local noon and shares ≥30°/≥40°; control: 2,000 random days of the same span. (2) Minimum separation during the night of the recorded date (18 h to 06 h local mean time, 30-min steps), median and shares ≤1.5°/≤5°, also with a ±1-day window; control: the same pairs on 400 random dates. Per-article values (g3_venus_articles, g3_appulse_articles) and the control draws (g3_*_control) are published.
- How to read it
- Distributions that separate from random mean the dates reflect the real sky. Absolute separations depend on which star a Chinese name denotes (dictionary of 16 star names — 15 positions, as names such as 房 and 鉤鈐 share one — and 6 planet names for 5 planets) and are indicative.
- Caveats
- Only pairs resolved by the dictionary were computed (Goryeosa 454, Ilgi 156; none for the Sillok, whose 1.0 keyword contexts are too short). Asterism names are represented by one star. Lee 2023's mean of 1.2° for 犯 in the Chunbang Ilgi comes from a precisely dated source and is not directly comparable.
- External check
- Lee 2023 (JKAS 56(1): 75–89, doi:10.5303/JKAS.2023.56.1.75; day counts on p. 77, separations on p. 85): Chunbang Ilgi, 1,443 days with astronomical records out of 2,799, mean separation 1.2° (±0.8) for 犯 and 1.0° (±0.6) for 食.
- Reliability card
- externalExternal match — compared with an astronomical computation
Goryeosa, 454 pairs: median separation that night 2.8°, with ±1 day 2.2°, ≤1.5° in 43%; the same pairs on random dates give a median of 91° and ≤5° in 1.8%.
The dictionary resolved 613 pairs out of 3,255 appulse-keyword articles.
| Source | Dated | Median elongation (°) | ≥30° | ≥40° | Evening share | Random median° | Random ≥30° |
|---|---|---|---|---|---|---|---|
| Goryeosa treatise | 171 | 43.0 | 90.1% | 65.5% | 54.4% | 30.4 | 50.5% |
| Jeolyo | 67 | 42.8 | 85.1% | 61.2% | 49.3% | 31.2 | 52.0% |
| Sillok | 3,767 | 43.6 | 93.8% | 70.3% | 52.6% | 30.5 | 50.9% |
| Ilgi | 23 | 42.2 | 87.0% | 60.9% | 56.5% | 31.0 | 51.8% |
| Source | Pairs | Median that night° | ≤1.5° | ≤5° | Median ±1 d° | ≤1.5° (±1 d) | ≤5° (±1 d) |
|---|---|---|---|---|---|---|---|
| Goryeosa treatise | 454 | 2.77 | 37.7% | 69.8% | 2.21 | 42.7% | 79.7% |
| Jeolyo | 3 | 0.09 | 100.0% | 100.0% | 0.09 | 100.0% | 100.0% |
| Ilgi | 156 | 3.13 | 28.2% | 67.3% | 2.65 | 31.4% | 79.5% |
| control (random dates, same pairs) | 400 | 90.82 | 0.3% | 1.8% |