Ptolemy (about 85-165 AD)
Claudius Ptolemaeus Pelusiniensis (Ptolemy) lived in Alexandria, Egypt
approximately 85-165 AD or 87-150 AD, and worked there as philosopher,
astronomer (and astrologer), mathemetician and geographer. He was of Greek
origin. He created a number of monumental and epochal works, above all the
Mathematical Syntaxis ("Megale Syntaxas tes Astronomias,"
Great Syntaxas of Astronomy), which became the foundation of more than a
millennium's astronomy, and is better known as Almagest
(Ptolemy, ca. 130 AD).
This work bound astronomical thinking in the western as well as the arabic
world to geocentrism, but also gave positions of the "fixed" stars, and 48
constellations still used today.
Other publications include his Geography, an early work of cartography
and geography, and the astrological work Tetrabiblos.
Within Almagest, he lists seven nebulous objects, 3 of which are
asterisms, but 4 are real deepsky objects; these are all open clusters.
Two of them, Praesepe (M44) and
the Double Cluster in h and Chi
in Perseus, have been taken from Hipparchus, but the other two are new:
the Coma Berenices Star Cluster (Mel 111)
and "A Nebula behind the Sting of Scorpius", actually open star cluster
M7 (now sometimes called Ptolemy's
Ptolemy's work was widely and longly used by the educated community.
In particular, his Almagest was used (and verified) by many consecutive
observers, notably Al Sufi (903-986 AD) and
Ulugh Begh (1394-1449).
Bigourdan (1892) has compiled a list including the
positions of the nebulous objects presumably observed by Ptolemy and
this list sorted by observer.
Nebulous objects mentioned in Ptolemy's Almagest:
No. Description Identification
175 In the right knee [of Cygnus] and 'nubisimilis' Omega1, Omega2 Cyg
191 At the tip of the right hand [of Perseus] and h and Chi Per
nebulous [or misty]
449 Center of the cloud-shaped convolutions in the Praesepe (M44)
breast [of Cancer], called Praesepe
494 Most northerly part of the convolutions which are 15 Com and Mel 111
called Coma Berenices, between the borders of Leo
and Ursa Major
567 Following the sting of Scorpius and nebulous M7
577 In the eye [of Sagittarius]; it is nebulous and Nu1, Nu2 Sgr
734 Nebulosity in Orion's Head Lambda, Phi1, Phi2 Ori
- Numbers are those in Bailly (1843), here taken
from Kenneth Glyn Jones (1968)
- No. 567 was identified by Bigourdan as open cluster
M7 (NGC 6475), a view is now generally
accepted. Previously, Peter and Knobel have identified it with the star
Gamma Telescopii (now G Sco) together with 8th-mag globular NGC 6441.
The latter view is now rejected because of that globular's faintness.
Honors and such:
- Ptolemy, ca. 130 AD.
Megale Syntaxas tes Astronomias (Almagest).
Ptolemy's Almagest was
available online at the MAA.
Almagestum (1515) is available online at the University of Vienna.
A translation of Ptolemy's catalog of stars is
available online thanks to Brian Tung and the Sternberg Astronomical
Institute of Moscow University.
- F. Baily, 1843.
Description of the Catalogues of Ptolemy, Ulugh Begh, Halley and Hevelius.
Mem. roy. astr. Soc., Vol. XIII.
- Guillaume Bigourdan, 1892.
Observations of 1884.
Observations de Nebuleuses et d'amas stellaires
[Observations of Nebulae and Star Clusters].
Annales de l'Observatoire de Paris (Observations).
of "neboulous stars" extracted from this work.
- Kenneth Glyn Jones, 1968.
The Search for the Nebulae -- I.
Journal of the British Astronomical Association, Vol. 78, No. 4 (1968),
p. 256-267. Section on Ptolemy: p. 261-263.
Reprinted in: The Search for the Nebulae. Chalfont St. Giles, 1975.
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