{
 "file": "sobral-astrographic.json",
 "kind": "transcription of printed tables (not a measurement of plate images)",
 "what": "The Sobral astrographic (13-inch object glass stopped to 8 inches, fed by a 16-inch coelostat) results as printed in the 1920 report: Table IX, the five-star declination table of p.311, the equations the report formed from it, its per-plate results, and the numbers on p.312.",
 "source": {
  "citation": "F. W. Dyson, A. S. Eddington and C. Davidson, \"A determination of the deflection of light by the sun's gravitational field, from observations made at the total eclipse of May 29, 1919\", Philosophical Transactions of the Royal Society of London, Series A, 220 (issues 571 to 581), 291 to 333. Received 30 October 1919, read 6 November 1919, published 27 April 1920. DOI 10.1098/rsta.1920.0009.",
  "doi": "10.1098/rsta.1920.0009",
  "scan_url": "https://astronomyforchange.org/wp-content/uploads/2021/06/DysonOriginalPaper_1919TSE_rsta.1920.0009.pdf",
  "scan_sha256": "f54474b217ab17a3d3bf4754cbe8bf0a1072c7a8f272696d1fb62d0ecc78350d",
  "scan_bytes": 8198432,
  "retrieved": "2026-09-22",
  "licence": "No licence statement on the scan (Royal Society download stamp). Only transcribed numbers, with citation, are shipped; the scan and its page images are not.",
  "pdf_page_note": "PDF page 1 is printed page 291; one plate page is bound in before printed page 293, so printed page p is PDF page p - 289 from page 293 on."
 },
 "pages": {
  "table_ix": "p.310 (PDF 21)",
  "five_star_table_and_equations": "p.311 (PDF 22)",
  "results": "p.312 (PDF 23)",
  "the_30_may_note_and_scale_sentence": "p.309 (PDF 20)"
 },
 "units": "micrometer revolutions (r) at 50 arcmin from the sun's centre",
 "screw_arcsec_per_rev": 12.3,
 "reference_distance_arcmin": 50,
 "sun_radius_arcmin": 15.8,
 "table_ix": [
  {
   "plate": 1,
   "comparison": "18_4",
   "n_stars": 7,
   "d": 0.051,
   "e": 0.089,
   "alpha": 0.033,
   "limb_arcsec": 1.28
  },
  {
   "plate": 2,
   "comparison": "18_4",
   "n_stars": 11,
   "d": -0.009,
   "e": 0.059,
   "alpha": 0.025,
   "limb_arcsec": 0.97
  },
  {
   "plate": 3,
   "comparison": "18_4",
   "n_stars": 8,
   "d": -0.074,
   "e": 0.101,
   "alpha": 0.028,
   "limb_arcsec": 1.09
  },
  {
   "plate": 4,
   "comparison": "18_4",
   "n_stars": 11,
   "d": -0.168,
   "e": 0.091,
   "alpha": 0.033,
   "limb_arcsec": 1.28
  },
  {
   "plate": 5,
   "comparison": "11_3",
   "n_stars": 10,
   "d": 0.094,
   "e": 0.076,
   "alpha": 0.025,
   "limb_arcsec": 0.97
  },
  {
   "plate": 6,
   "comparison": "11_3",
   "n_stars": 11,
   "d": 0.186,
   "e": 0.082,
   "alpha": 0.021,
   "limb_arcsec": 0.82
  },
  {
   "plate": 7,
   "comparison": "14_3",
   "n_stars": 12,
   "d": 0.006,
   "e": 0.119,
   "alpha": 0.0,
   "limb_arcsec": 0.0
  },
  {
   "plate": 7,
   "comparison": "18_3",
   "n_stars": 7,
   "d": -0.054,
   "e": 0.166,
   "alpha": 0.0,
   "limb_arcsec": 0.0
  },
  {
   "plate": 8,
   "comparison": "14_3",
   "n_stars": 10,
   "d": 0.093,
   "e": 0.064,
   "alpha": 0.021,
   "limb_arcsec": 0.82
  },
  {
   "plate": 9,
   "comparison": "17_4",
   "n_stars": 7,
   "d": -0.096,
   "e": 0.129,
   "alpha": 0.008,
   "limb_arcsec": 0.31
  },
  {
   "plate": 10,
   "comparison": "17_4",
   "n_stars": 10,
   "d": 0.09,
   "e": 0.045,
   "alpha": 0.026,
   "limb_arcsec": 1.01
  },
  {
   "plate": 11,
   "comparison": "11_1",
   "n_stars": 10,
   "d": 0.073,
   "e": 0.061,
   "alpha": 0.032,
   "limb_arcsec": 1.24
  },
  {
   "plate": 12,
   "comparison": "11_1",
   "n_stars": 11,
   "d": -0.009,
   "e": 0.102,
   "alpha": 0.049,
   "limb_arcsec": 1.91
  },
  {
   "plate": 12,
   "comparison": "17_2",
   "n_stars": 7,
   "d": -0.102,
   "e": 0.114,
   "alpha": 0.019,
   "limb_arcsec": 0.74
  },
  {
   "plate": 15,
   "comparison": "15_3",
   "n_stars": 6,
   "d": 0.111,
   "e": 0.036,
   "alpha": 0.018,
   "limb_arcsec": 0.7
  },
  {
   "plate": 16,
   "comparison": "15_3",
   "n_stars": 7,
   "d": -0.002,
   "e": 0.037,
   "alpha": 0.018,
   "limb_arcsec": 0.7
  },
  {
   "plate": 17,
   "comparison": "17_2",
   "n_stars": 8,
   "d": -0.022,
   "e": 0.109,
   "alpha": 0.012,
   "limb_arcsec": 0.47
  },
  {
   "plate": 18,
   "comparison": "17_2",
   "n_stars": 7,
   "d": 0.045,
   "e": 0.0,
   "alpha": 0.03,
   "limb_arcsec": 1.17
  }
 ],
 "table_ix_printed_means": {
  "e": 0.082,
  "alpha": 0.022,
  "limb_arcsec": 0.86
 },
 "five_star": {
  "stars": [
   5,
   4,
   3,
   6,
   10
  ],
  "dy": {
   "1": [
    -0.051,
    0.175,
    0.169,
    0.201,
    0.235
   ],
   "2": [
    0.558,
    0.656,
    0.724,
    0.668,
    0.702
   ],
   "3": [
    0.124,
    0.285,
    0.286,
    0.274,
    0.355
   ],
   "4": [
    0.111,
    0.222,
    0.247,
    0.231,
    0.167
   ],
   "5": [
    0.034,
    0.228,
    0.232,
    0.218,
    0.308
   ],
   "6": [
    0.164,
    0.488,
    0.478,
    0.557,
    0.637
   ],
   "7": [
    -0.051,
    0.156,
    0.162,
    0.25,
    0.279
   ],
   "8": [
    0.108,
    0.33,
    0.314,
    0.376,
    0.397
   ],
   "9": [
    -0.059,
    0.121,
    0.109,
    0.205,
    0.18
   ],
   "10": [
    0.033,
    0.27,
    0.188,
    0.258,
    0.28
   ],
   "11": [
    0.025,
    0.215,
    0.21,
    0.233,
    0.274
   ],
   "12": [
    -0.068,
    0.144,
    0.124,
    0.16,
    0.167
   ],
   "15": [
    -0.038,
    0.138,
    0.107,
    0.172,
    null
   ],
   "16": [
    -0.05,
    0.076,
    0.046,
    0.127,
    0.073
   ],
   "17": [
    -0.071,
    0.104,
    0.081,
    0.186,
    0.164
   ],
   "18": [
    0.016,
    0.092,
    0.109,
    0.099,
    0.084
   ]
  },
  "note": "Plate 15 does not show star 10 (p.312: \"In photograph No. 15, star 10 is not shown, and the equation is slightly modified\")."
 },
 "equations_p311": {
  "5": {
   "d": -0.16,
   "e": -1.107,
   "alpha": -0.789
  },
  "4": {
   "d": 0.334,
   "e": 0.472,
   "alpha": 1.336
  },
  "3": {
   "d": 0.348,
   "e": 0.36,
   "alpha": 1.574
  },
  "6": {
   "d": 0.587,
   "e": 1.099,
   "alpha": 0.726
  },
  "10": {
   "d": 0.86,
   "e": 1.321,
   "alpha": 0.589
  }
 },
 "combination_p311": {
  "weights": {
   "4": 1,
   "3": 1,
   "5": -1,
   "6": -0.5,
   "10": -0.5
  },
  "printed": {
   "alpha": 3.041,
   "e": 0.729,
   "d": 0.118
  },
  "weights_without_star_10": {
   "4": 1,
   "3": 1,
   "5": -1,
   "6": -1
  }
 },
 "printed_alpha_plus_ce": {
  "1": {
   "coef": 0.24,
   "value": 0.056
  },
  "2": {
   "coef": 0.24,
   "value": 0.049
  },
  "3": {
   "coef": 0.24,
   "value": 0.047
  },
  "4": {
   "coef": 0.24,
   "value": 0.059
  },
  "5": {
   "coef": 0.24,
   "value": 0.05
  },
  "6": {
   "coef": 0.24,
   "value": 0.059
  },
  "7": {
   "coef": 0.24,
   "value": 0.036
  },
  "8": {
   "coef": 0.24,
   "value": 0.046
  },
  "9": {
   "coef": 0.24,
   "value": 0.035
  },
  "10": {
   "coef": 0.24,
   "value": 0.048
  },
  "11": {
   "coef": 0.24,
   "value": 0.045
  },
  "12": {
   "coef": 0.24,
   "value": 0.059
  },
  "15": {
   "coef": 0.283,
   "value": 0.026
  },
  "16": {
   "coef": 0.24,
   "value": 0.024
  },
  "17": {
   "coef": 0.24,
   "value": 0.028
  },
  "18": {
   "coef": 0.24,
   "value": 0.029
  }
 },
 "printed": {
  "mean_alpha_plus_ce_r": 0.0435,
  "mean_coef": 0.243,
  "mean_coef_as_printed": "243e (the decimal point is not printed)",
  "e_from_table_ix_r": 0.082,
  "alpha_at_table_ix_e_r": 0.024,
  "limb_at_table_ix_e_arcsec": 0.93,
  "e_refraction_aberration_r": 0.02,
  "alpha_at_refraction_e_r": 0.039,
  "limb_at_refraction_e_arcsec": 1.52,
  "perplate_lsq_limb_arcsec": 0.99,
  "table_ix_mean_limb_arcsec": 0.86
 }
}