{
    "version": 2,
    "description": "ΔT(TT-UT, 초) 계산용 공용 계수와 ΔT 불확실성 표. PHP와 JS가 모두 이 파일만 읽는다.",
    "sources": [
        "Stephenson, Morrison & Hohenkerk (2016), Proc. R. Soc. A 472:20160404",
        "Morrison, Stephenson, Hohenkerk & Zawilski (2021 Addendum), Proc. R. Soc. A 477:20200776",
        "UKHO NAO Table-S15.2020.txt",
        "https://github.com/ytliu0/DeltaT (DeltaT.py)"
    ],
    "spline": {
        "y0": [-720, -100, 400, 1000, 1150, 1300, 1500, 1600, 1650, 1720, 1800,
            1810, 1820, 1830, 1840, 1850, 1855, 1860, 1865, 1870, 1875, 1880,
            1885, 1890, 1895, 1900, 1905, 1910, 1915, 1920, 1925, 1930, 1935,
            1940, 1945, 1950, 1953, 1956, 1959, 1962, 1965, 1968, 1971, 1974,
            1977, 1980, 1983, 1986, 1989, 1992, 1995, 1998, 2001, 2004, 2007,
            2010, 2013, 2016, 2019, 2022],
        "y1": [-100, 400, 1000, 1150, 1300, 1500, 1600, 1650, 1720, 1800, 1810,
            1820, 1830, 1840, 1850, 1855, 1860, 1865, 1870, 1875, 1880, 1885,
            1890, 1895, 1900, 1905, 1910, 1915, 1920, 1925, 1930, 1935, 1940,
            1945, 1950, 1953, 1956, 1959, 1962, 1965, 1968, 1971, 1974, 1977,
            1980, 1983, 1986, 1989, 1992, 1995, 1998, 2001, 2004, 2007, 2010,
            2013, 2016, 2019, 2022, 2025],
        "a0": [20371.848, 11557.668, 6535.116, 1650.393, 1056.647, 681.149, 292.343,
            109.127, 43.952, 12.068, 18.367, 15.678, 16.516, 10.804, 7.634,
            9.338, 10.357, 9.04, 8.255,
            2.371, -1.126, -3.21, -4.388, -3.884, -5.017, -1.977, 4.923, 11.142,
            17.479, 21.617, 23.789, 24.418, 24.164, 24.426, 27.05, 28.932,
            30.002, 30.76, 32.652, 33.621, 35.093, 37.956, 40.951, 44.244,
            47.291, 50.361, 52.936, 54.984, 56.373, 58.453, 60.678, 62.898,
            64.083, 64.553, 65.197, 66.061, 66.919, 68.130, 69.250, 69.296],
        "a1": [-9999.586, -5822.27, -5671.519, -753.21, -459.628, -421.345,
            -192.841, -78.697, -68.089, 2.507, -3.481, 0.021, -2.157, -6.018,
            -0.416, 1.642, -0.486, -0.591, -3.456, -5.593, -2.314, -1.893, 0.101,
            -0.531, 0.134, 5.715, 6.828, 6.33, 5.518, 3.02, 1.333, 0.052, -0.419,
            1.645, 2.499, 1.127, 0.737, 1.409, 1.577, 0.868, 2.275, 3.035, 3.157,
            3.199, 3.069, 2.878, 2.354, 1.577, 1.648, 2.235, 2.324, 1.804, 0.674,
            0.466, 0.804, 0.839, 1.005, 1.348, 0.594, -0.227],
        "a2": [776.247, 1303.151, -298.291, 184.811, 108.771, 61.953, -6.572,
            10.505, 38.333, 41.731, -1.126, 4.629, -6.806, 2.944, 2.658, 0.261,
            -2.389, 2.284, -5.148, 3.011, 0.269, 0.152, 1.842, -2.474, 3.138,
            2.443, -1.329, 0.831, -1.643, -0.856, -0.831, -0.449, -0.022, 2.086,
            -1.232, 0.22, -0.61, 1.282, -1.115, 0.406, 1.002, -0.242, 0.364,
            -0.323, 0.193, -0.384, -0.14, -0.637, 0.708, -0.121, 0.21, -0.729,
            -0.402, 0.194, 0.144, -0.109, 0.275, 0.068, -0.822, 0.001],
        "a3": [409.16, -503.433, 1085.087, -25.346, -24.641, -29.414, 16.197, 3.018,
            -2.127, -37.939, 1.918, -3.812, 3.25, -0.096, -0.539, -0.883, 1.558,
            -2.477, 2.72, -0.914, -0.039, 0.563, -1.438, 1.871,
            -0.232, -1.257, 0.72, -0.825, 0.262, 0.008, 0.127, 0.142, 0.702,
            -1.106, 0.614, -0.277, 0.631, -0.799, 0.507, 0.199, -0.414, 0.202,
            -0.229, 0.172, -0.192, 0.081, -0.165, 0.448, -0.276, 0.11, -0.313,
            0.109, 0.199, -0.017, -0.084, 0.128, -0.069, -0.297, 0.274, 0.086]
    },
    "extrapolation": {
        "spline_start_year": -720,
        "spline_end_year": 2025,
        "c1_before_start": 1.007739546148514,
        "c2_after_end": -150.56787057979514,
        "lod_center_year": 1825,
        "lod_t_scale": 0.01,
        "lod_quadratic": 31.4115,
        "lod_cos_amplitude": 284.8435805251424,
        "lod_cos_frequency": 0.4487989505128276,
        "lod_cos_phase": 0.75
    },
    "tidal": {
        "smh_dalpha_arcsec_cy2": -25.82,
        "de441_dalpha_arcsec_cy2": -25.936,
        "coefficient": 0.91072,
        "t_center": 19.55,
        "t_scale": 0.01
    },
    "uncertainty": {
        "description": "ΔT 표준오차(초). years[i] <= 연도 < years[i+1] 구간에서는 seconds[i]를 그대로 쓰는 계단함수(보간 없음). 표 밖은 k * (연도 - center_year)^2 로 외삽.",
        "years": [
            -2000, -1600, -900, -720, -700, -600, -500, -400, -300, -200, -100, 0, 100, 200,
            300, 400, 500, 700, 800, 900, 1000, 1620, 1660, 1670, 1680, 1730, 1770, 1800, 1802,
            1805, 1809, 1831, 1870, 2025, 2025.5, 2026, 2030, 2040, 2050, 2100, 2200, 2300,
            2400, 2500],
        "seconds": [
            1080, 720, 360, 180, 170, 160, 150, 130, 120, 110, 100, 90, 80, 70, 60, 50, 40, 30,
            25, 20, 15, 20, 15, 10, 5, 2, 1, 0.5, 0.4, 0.3, 0.2, 0.1, 0.05, 0.1, 0.2, 1, 2, 4,
            6, 10, 20, 30, 50, 100],
        "extrapolation": {
            "center_year": 1825,
            "k_before_table": 0.74e-4,
            "k_after_table": 2.2e-4
        }
    }
}