DISCOVERY OF HIPPARCHUS

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DISCOVERY OF HIPPARCHUS LOST STAR CATALOG ON THE
FARNESE ATLASBRADLEY E. SCHAEFER(Louisiana
State University)
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HIPPARCHUS -Greatest Astronomer of Antiquity
Rhodes fl. 140-125 BC Only surviving work is his
Commentary

• First Star Catalog (1000 stars)
• Discovered Precession
• First Nova
• First Model for Solar Lunar Motion
• Best Planetary Observations to Date

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• FARNESE ATLAS SHOWS
• 41 Constellations
• (no stars)
• Equator, Tropics
• Colures
• Arctic, Antarctic Circles

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POSSIBLE DATES FOR OBSERVATIONS USED TO PLACE THE
CONSTELLATIONS

• c. 150 AD Contemporary with Roman sculptor
• c. 128 AD From Ptolemys Almagest
• c. 275 BC From Aratus Phaenomena
• c. 366 BC From Eudoxus Phaenomena
• 113080 BC Assyrian observer who was source for
  Eudoxus and MUL.APIN

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GET DATE FROM CONSTELLATION POSITIONS

• Constellations positions shift slowly with the
  centuries (due to precession), so the depicted
  positions provide a clock

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PRECESSION
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DATE OF FARNESE ATLAS CONSTELLATION DATA

• New photographs taken in Naples last June
• New photos required as camera-globe distance
  must be known for photogrammetry
• 70 constellation positions measured to 1.5
  accuracy
• Chi-square fit to find the best date
• ? 125 BC (55 years)
• ? REJECTS Ptolemy, Aratus, Eudoxus, and
  the Assyrian ? MATCHES Hipparchus

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DATE OF FARNESE ATLAS CONSTELLATION DATA

• Accuracy of original data is lt2
• Ancient star catalogs have accuracy lt1
• Ancient verbal descriptions have accuracy gt4-8
• ? Original data must be from a star catalog
• ? Only Hipparchus and Ptolemy
• have old star catalogs
• (and Ptolemy is too late)

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DETAILED COMPARISON BETWEEN ATLAS AND ANCIENT
SOURCES

• Phaenomena of Aratus Eudoxus
• 12 significant differences
• e.g., solstice off by 35!, Centaur not under
  Scorpion, Eridanus extends almost to Dog
• Commentaries of Hipparchus
• 0 differences
• Catasterismi of Pseudo-Eratosthenes
  Eratosthenes
• 9 significant differences
• e.g., Southern Crown is present, Hercules is
  kneeling, Pegasus has wings
• Almagest of Ptolemy
• 11 significant differences
• e.g., Equuleus and Bernices Hair missing,
  Eridanus extends almost to Dog, Archer has no
  cloak

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CONNECTING THE FARNESE ATLAS TO HIPPARCHUS
CATALOG

• 3.5 ACCURACY REQUIRES A STAR CATALOG
• ?Only Hipparchus and Ptolemy have ancient star
  catalog
• FARNESE ATLAS POSITIONS FROM 125 55 BC
• ?Eliminates Ptolemy, Aratus, Eudoxus, the
  Assyrian, and any contemporary
• ?Only Hipparchus is consistent with date
• CONSTELLATION ICONS MATCH HIPPARCHUS
• ?Eliminates Ptolemy, Aratus, Eudoxus, and
  Eratosthenes
• ?Only Hipparchus matches the Farnese Atlas
• ? FARNESE ATLAS BASED ON THE LOST STAR CATALOG OF
  HIPPARCHUS

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APPLICATIONS

• WHAT COORDINATE SYSTEM DID HIPPARCHUS USE?
• None? Equatorial? Ecliptic? Mixed?
• EQUATOR, COLURES, TROPICS ? EQUATORIAL
  COORDINATES
• HOW MUCH OF HIPPARCHUS CATALOG IS IN THE
  ALMAGEST?
• None? Small fraction? Large fraction? All?
  
• In past, we have only had partial positions for
  some stars (from the Commentary) are known, and
  these have an unknown relation to the star
  catalog
• NOW, WE HAVE HIPPARCHUS FULL CATALOG ?
• FUTURE WORKERS WILL TEST FARNESE ATLAS vs.
  ALMAGEST

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CONCLUSIONS

• THE LOST STAR CATALOG OF HIPPARCHUS IS DEPICTED
  ON THE FARNESE ATLAS