J/A+A/544/A31 Star catalogues of Ptolemaios, Ulugh Beg (Verbunt+, 2012)
The star catalogues of Ptolemaios and Ulugh Beg.
Verbunt, F., van Gent, R.H.
<Astron. Astrophys. 544, A31 (2012)>
=2012A&A...544A..31V 2012A&A...544A..31V
ADC_Keywords: Historical catalog ; Positional data
Keywords: astrometry - history and philosophy of astronomy
Abstract:
In late antiquity and throughout the middle ages, the positions of
stars on the celestial sphere were obtained from the star catalogue of
Ptolemaios. A catalogue based on new measurements appeared in 1437,
with positions by Ulugh Beg, and magnitudes from the 10th-century
astronomer al-Sufi. We provide machine-readable versions of these two
star catalogues, based on the editions by Toomer (1998) and Knobel
(1917), and determine their accuracies by comparison with the modern
Hipparcos Catalogue. The magnitudes in the catalogues correlate well
with modern visual magnitudes; the indication `faint' by Ptolemaios is
found to correspond to his magnitudes 5 and 6. Gaussian fits to the
error distributions in longitude/latitude give widths sigma
∼27-arcmin/23-arcmin in the range
|Δλ,Δβ|<50-arcmin for Ptolemaios and
σ∼22-arcmin/18-arcmin in Ulugh Beg. Fits to the range
|Δλ,Δβ<100-arcmin gives 10-15 per cent larger
widths, showing that the error distributions are broader than
gaussians. The fraction of stars with positions wrong by more than
150-arcmin is about 2 per cent for Ptolemaios and 0.1 percent in Ulugh
Beg; the numbers of unidentified stars are 1 in Ptolemaios and 3 in
Ulugh Beg. These numbers testify to the excellent quality of both star
catalogues (as edited by Toomer and Knobel).
Description:
We present Machine-readable versions of the star catalogues of
Ptolemaios (137) and Ulugh Beg (1437). In addition to the data from
the historical catalogues, the machine-readable version contains the
modern identification with a Hipparcos star and the latter's
magnitude, and based on this identification the positional accuracy.
For Ulugh Beg's catalogue we also give cross references to the
catalogue of Ptolemaios.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
ptolema.dat 78 1028 Star Catalogue of Ptolemaios (137)
ulughbeg.dat 88 1018 Star Catalogue of Ulugh Beg (1437)
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See also:
V/61 : Almagest (Ptolemy's Star Catalog)
J/A+A/516/A28 : Star catalogue of Tycho Brahe (1627) (Verbunt+, 2010)
J/A+A/516/A29 : Star catalogue of Hevelius (1690) (Verbunt+, 2010)
J/A+A/530/A93 : de Houtman, Kepler and Halley star catalogs (Verbunt+ 2011)
Byte-by-byte Description of file: ptolema.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- P [1/1028] Sequence number in Ptolemaios Catalogue
6- 7 I2 --- C [1/48] Constellation sequence number
9- 12 A4 --- cst Abbreviation of constellation name
14- 15 I2 --- N [1/45] Sequence number of star in constellation
16 A1 --- f_N [a] 'a' for star outside the constellation figure
19- 20 I2 30deg Elon.Z [1/12] Zodiacal sign of longitude (1)
22- 23 I2 deg Elon.d [0/30] Longitude (degrees) (1)
25- 26 I2 arcmin Elon.m [0/59] Longitude (arcmin) (1)
29- 30 I2 deg Elat.d [0/90] Ecliptic latitude (degrees) (2)
32- 33 I2 arcmin Elat.m [0/60] Ecliptic latitude (arcmin) (2)
35 A1 --- Elat.- [AB] Sign of latitude (2)
38 I1 --- VP [1/9] Magnitude as given by Ptolemaios (3)
39 A1 --- q_VP [bf] brighter/fainter qualifier by Ptolemaios (G1)
41- 46 I6 --- HIP ?=0 Hipparcos number of identification
48 I1 --- I [1/6] Quality of identification flag (G2)
50 I1 --- T [0/3] Comparison flag with Toomer (4)
52- 55 F4.1 mag Vmag Johnson V magnitude (from Hipparcos)
57- 62 F6.1 arcmin Dl Difference in longitude (Hipparcos-Ptolemaios)
64- 69 F6.1 arcmin Db Difference in latitude (Hipparcos-Ptolemaios)
71- 76 F6.1 arcmin dist Distance Δ between Ptolemaios and
Hipparcos positions
78 A1 --- Flag [*] Flag for annotation in article
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Note (1): The longitude is given by Elon =(Elon.Z-1)*30+Elon.d+Elon.m/60
(assumed Equinox=-128, corresponding to Hipparchos observations)
Note (2): The latitude is given by Elat=Elat.d+Elat.m/60 for boreal stars
('B' in Elat.-); the sign of the latitude is changed for austral stars
('A' in Elat.-).
Note (3): Special values: 7=faint, 9=nebulous
Note (4): Comparison flag with Toomer as follows:
1 = same identification in Toomer
2 = identification in Toomer is one of two plausible identifications
3 = identification in Toomer is incompatible with ours
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Byte-by-byte Description of file: ulughbeg.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- U [1/1018] Sequence number in Ulugh Beg Catalogue
5 A1 --- n_U [c] 'c' when the position is derived
from Ptolemaios via al-Sufi
7- 10 I4 --- P Corresponding sequence number of in Ptolemaios
13- 14 I2 --- C Sequence number of constellation
16- 19 A4 --- cst Abbreviation of constellation name
21- 22 I2 --- N Sequence number of star in constellation
23 A1 --- n_N [a] 'a' for star outside the constellation figure
26- 27 I2 30deg Elon.Z [0/11] Zodiacal sign (1)
29- 30 I2 deg Elon.d Degrees of longitude (1)
32- 33 I2 arcmin Elon.m Minutes of longitude (1)
37- 38 I2 deg Elat.d Degrees of ecliptic latitude (2)
40- 41 I2 arcmin Elat.m Arcminutes of ecliptic latitude (2)
43 A1 --- Elat.- Sign of latitude (2)
46 I1 --- VU Magnitude as given by Ulugh Beg (3)
47 A1 --- q_VU [bf] brighter/fainter qualifier by Ulugh Beg (G1)
49- 54 I6 --- HIP ?=0 Hipparcos number of identification
56 I1 --- I Flag indicating quality of identification (G2)
58 I1 --- K [0/3] Comparison flag with Knobel (4)
60 I1 --- I-P [0/3] Comparison flag with Ptolemaios (5)
62- 65 F4.1 mag Vmag Johnson V magnitude (from Hipparcos)
67- 72 F6.1 arcmin Dl Difference in longitude (Hipparcos-UlughBeg)
74- 79 F6.1 arcmin Db Difference in latitude (Hipparcos-UlughBeg)
81- 86 F6.1 arcmin dist Distance {Dleta} between UlughBeg and
Hipparcos positions
88 A1 --- Flag [*] Flag for annotation in article
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Note (1): The longitude is given by Elon =(Elon.Z)*30+Elon.d+Elon.m/60
(Equinox=1437)
Note (2): The latitude is given by Elat=Elat.d+Elat.m/60 for boreal stars
('B' in Elat.-); the sign of the latitude is changed for austral stars
('A' in Elat.-).
Note (3): Special values: 8=not seen, 9=nebulous
Note (4): Comparison flag with Knobel as follows:
0 = unidentified in Knobel
1 = same identification in Knobel as ours
2 = identification in Knobel is one of two plausible identifications
3 = identification in Knobel is incompatible with ours
Note (5): Comparison flag with Ptolemaios as follows:
0 = corresponding star in Ptolemaios is unidentified
1 = corresponding star in Ptolemaios has same identification
2 = corresponding star in Ptolemaios has alternative identification
3 = corresponding star in Ptolemaios has different identification
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Global notes:
Note (G1): Qualifier as follows:
f = somewhat fainter
b = somewhat brighter
Note (G2): Quality of identification flag as follows:
1 = secure identification with nearest star
2 = secure identification, even though not nearest star
3 = probable identification
4 = possible identification
5 = not identified
6 = repeated entry
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Acknowledgements:
Frank Verbunt, Dept.Astrophysics Radboud University Nijmegen
F.Verbunt(at)astro.ru.nl
(End) Frank Verbunt [Radboud Univ. Nijmegen], Patricia Vannier [CDS] 05-Jun-2012