Coordinate System

V12 current — H(r) exponential curve — mean error 5.2%, median 4.4%

V12 Coordinate System (Current)

Key V50.6 discovery: H is not constant. The firmament curves downward from pole toward rim.

H(r) = 8537 × exp(−r / 8619) km

r(city) = solve numerically:  r × tan(polaris_elevation) = H(r)
θ        = Δlon × 0.9941   (EW angular scale)
distance = sqrt(r1² + r2² − 2 × r1 × r2 × cos(Δθ))
where    Δθ = Δlon × 0.9941

Performance: mean 5.2%, median 4.4% across 19 city pairs (was ~40% in V9).

V9 Reference (Superseded by V12)

V9 used flat H=4,750 km and solar noon UTC as theta proxy. V50.6 replaced both with H(r) exponential and Δlon × 0.9941.

Southern Hemisphere

Input:  Solar noon altitude at June solstice + solar noon UTC
Output: r, θ

lat_S = 90 − noon_altitude_june + 23.44     (June dec = −23.44°)
r     = H / tan(lat_S)
θ     = (solar_noon_utc − 12.0) × 15°

Distance Formula (V9 — Law of Cosines)

d = sqrt(r1² + r2² − 2 × r1 × r2 × cos(Δθ))

Correct for polar disc geometry.
Arc formula d = r_avg × Δθ used in V1–V8 is only valid for very small Δθ.
Replaced at V9.

Ellipse Correction

r_ellipse(θ) = (a × b) / sqrt((b × cos(θ − orient))² + (a × sin(θ − orient))²)

a ≈ 20,015 km     (semi-major, pole to equatorial boundary)
b ≈ 15,000 km     (semi-minor, refining)
b/a = 0.70–0.90   (V5–V9 range, converging)
orient ≈ 60°       (NE from Greenwich, Atlantic-to-Asia axis)

Ellipse-over-circle: LOCKED. Ellipse outperforms circle across all versions (WIN-030). Parameters: not yet locked — WGS84 contamination in source coordinates (OPEN-001). V10 will use sunrise/sunset times only.

Known Issues (Honest)

IssueV9 ErrorV12 StatusFix
Oslo-Stockholm−89%0.0% — RESOLVEDV12 H(r) + correct θ from longitude
Southern over-predictionQuadratic with latitudeReduced (V12 EW scale)Further refinement with dome-native coords
Cross-equator25–78% on long pairsUnder revisionV12 H(r) + ellipse

Northern Hemisphere City Coordinates (H = 4,750 km)

CityPolaris °Noon UTCr (km)θ °x (km)y (km)
North Pole89.990.001−180.0−10
Reykjavik64.1013.932,306+28.92,0181,116
Anchorage61.2022.802,611+162.0−2,484807
Oslo59.9012.232,753+3.52,748166
Stockholm59.3312.072,817+1.12,81754
Moscow55.759.573,234−36.42,601−1,921
London51.5012.003,778+0.03,7780
Warsaw52.2010.603,684−21.03,440−1,320
Berlin52.5011.073,645−13.93,537−879
Paris48.9011.854,144−2.34,140−163
Chicago41.8817.805,298+87.02775,290
Istanbul41.019.475,462−37.94,307−3,359
Madrid40.4212.475,577+7.15,535685
New York40.7116.875,520+73.11,6095,281
Denver39.7319.135,715+106.9−1,6665,467
Chapel Hill NC36.1817.256,495+78.81,2676,370
Tokyo35.702.736,610−139.0−4,993−4,332
Los Angeles34.0519.877,029+118.1−3,3056,203
Cairo30.109.878,194−32.06,953−4,336
Baghdad33.308.477,231−52.94,357−5,771
Miami25.8017.279,826+79.01,8669,647
Mexico City19.4318.6013,466+99.0−2,10713,300
Mumbai19.086.2013,733−87.0719−13,714
Hong Kong22.323.8011,570−123.0−6,302−9,704

Southern Hemisphere City Coordinates

CityNoon Alt (June)Noon UTClat_S °r (km)θ °x (km)y (km)
Sydney33.0°14.1733.6°S7,160+32.56,0353,852
Cape Town33.6°10.0033.0°S7,326−30.06,344−3,663
Buenos Aires33.5°15.8733.1°S7,298+58.03,8626,192
Santiago37.0°16.8729.6°S8,375+73.12,4428,011
Melbourne30.0°14.4036.6°S6,405+36.05,1823,765
Auckland23.5°14.2743.1°S5,083+34.04,2122,846
Johannesburg42.0°9.7324.6°S10,394−34.08,612−5,820
Perth38.0°12.1328.6°S8,727+2.08,722297

What Changed V9 → V50.6

  1. H(r) = 8537×exp(−r/8619) — Firmament height is not constant. Pure exponential fit.
  2. θ = Δlon × 0.9941 — EW angular scale replaces solar noon proxy. Fixed V9 theta bug.
  3. Numerical r solve — r × tan(polaris) = H(r) solved iteratively. No flat-H assumption.
  4. H reconciliation — Schumann (~9,500 km), Polaris (4,750 km), model (9,086 km) all sampling same H(r) curve at different r.
  5. Oslo-Stockholm resolved — 0.0% error. V9 bug was wrong θ + flat H.