{
 "file": "sobral-4inch.json",
 "kind": "transcription of printed tables (not a measurement of plate images)",
 "what": "The Sobral 4-inch lens reduction as printed in the 1920 report: Table II (per-star differences, eclipse and comparison plates), the equations of condition, the normal equations of Tables III to VI with their printed solutions, Table VII and the printed derivation of the headline.",
 "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": {
  "screw_value": "p.302 (PDF 13)",
  "table_ii": "p.303 (PDF 14), printed rotated",
  "conditions": "p.304 (PDF 15)",
  "tables_iii_to_vi": "pp.304 to 305 (PDF 15 to 16)",
  "table_vii_and_derivation": "p.306 (PDF 17)",
  "alternatives": "p.291 (PDF 1)",
  "conclusions": "pp.330 to 332 (PDF 41 to 43)"
 },
 "units": "micrometer screw revolutions (r)",
 "screw_arcsec_per_rev": 6.25,
 "reference_distance_arcmin": 50,
 "sun_radius_arcmin": 15.8,
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  "einstein_limb_arcsec": 1.75,
  "page": "p.291"
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   "printed": -0.789,
   "implied": -0.798,
   "evidence": "All four printed right-hand sides for eclipse plate I in right ascension (Table III) are reproduced to 0.001 by -0.798; the printed -0.789 leaves 0.009 in the first row. Read on the 600 dpi render: the table prints -0.789."
  },
  {
   "set": "comparison",
   "plate": "14_2a",
   "coord": "Dx",
   "star": 2,
   "printed": -0.396,
   "implied": -0.346,
   "evidence": "All four printed right-hand sides for comparison plate 14_2a in right ascension (Table IV) are reproduced to 0.001 by -0.346; the printed -0.396 leaves 0.051 in the first row. Read on the 600 dpi render: the table prints -0.396."
  },
  {
   "set": "eclipse",
   "plate": "VIII",
   "coord": "Dy",
   "offset": true,
   "printed": -1.322,
   "implied": -1.332,
   "evidence": "The number below the line for eclipse plate VIII in declination is printed -1.322 (600 dpi render); all four printed right-hand sides of Table V for plate VIII are reproduced by -1.332, which is also star 5's value on that plate, the pattern on every other eclipse plate. Offsets do not affect alpha."
  },
  {
   "set": "residual",
   "note": "Three declination sets (eclipse I, comparison 15_1, comparison 17_2) disagree with their printed normal equations only in the Ey row, by about 0.009, 0.009 and 0.005. No single cell or offset explains them. They are reported, not corrected."
  }
 ]
}