discovery of hipparchus’ lost star catalog on the farnese atlas bradley e. schaefer (louisiana...
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DISCOVERY OF HIPPARCHUS’ LOST STAR CATALOG ON
THE FARNESE ATLAS
BRADLEY E. SCHAEFER(Louisiana State University)
HIPPARCHUS -Greatest Astronomer of Antiquity
• First Star Catalog (~1000 stars)• Discovered Precession• First Nova• First Model for Solar & Lunar
Motion• Best Planetary Observations to
Date
Rhodes: fl. 140-125 BCOnly surviving work is his Commentary
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 Ptolemy’s Almagest• c. 275 BC From Aratus’ Phaenomena• c. 366 BC From Eudoxus’ Phaenomena• 1130±80 BCAssyrian observer who was source for
Eudoxus and MUL.APIN
GET DATE FROM CONSTELLATION POSITIONS
Constellations positions shift slowly with the centuries (due to precession), so the depicted positions provide a ‘clock’
PRECESSION
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DATE OF FARNESE ATLAS CONSTELLATION DATA
• New photographs taken in Naples last JuneNew 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
DATE OF FARNESE ATLAS CONSTELLATION DATA
• Accuracy of original data is <2°• Ancient star catalogs have accuracy <1°• Ancient verbal descriptions have accuracy >4°-8°
Original data must be from a star catalog
Only Hipparchus and Ptolemyhave old star catalogs
(and Ptolemy is too late)
DETAILED COMPARISON BETWEEN ATLAS AND ANCIENT SOURCES
• Phaenomena of Aratus & Eudoxus12 significant differences
e.g., solstice off by 35°!, Centaur not under Scorpion, Eridanus extends almost to Dog
• Commentaries of Hipparchus0 differences
• Catasterismi of Pseudo-Eratosthenes & Eratosthenes9 significant differences
e.g., Southern Crown is present, Hercules is kneeling, Pegasus has wings
• Almagest of Ptolemy11 significant differences
e.g., Equuleus and Bernices’ Hair missing, Eridanus extends almost to Dog, Archer has no cloak
CONNECTING THE FARNESE ATLAS TO HIPPARCHUS’ CATALOG
• 3.5° ACCURACY REQUIRES A STAR CATALOGOnly Hipparchus and Ptolemy have ancient star catalog
• FARNESE ATLAS POSITIONS FROM 125 ± 55 BCEliminates Ptolemy, Aratus, Eudoxus, the Assyrian, and any contemporaryOnly Hipparchus is consistent with date
• CONSTELLATION ICONS MATCH HIPPARCHUSEliminates Ptolemy, Aratus, Eudoxus, and EratosthenesOnly Hipparchus matches the Farnese Atlas
FARNESE ATLAS BASED ON THE LOST STAR CATALOG OF HIPPARCHUS
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
CONCLUSIONSTHE LOST STAR
CATALOG OF HIPPARCHUS IS DEPICTED ON THE FARNESE ATLAS
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