I/90 Positions of 502 Stars in Pleiades Region (Eichhorn+ 1970)
Accurate Positions of 502 Stars in the Region of the Pleiades
Eichhorn H., Googe W.D., Lukac C.F., Murphy J.K.
<Mem. Roy. Astron. Soc. 73, 125 (1970)>
=1970MmRAS..73..125E 1970MmRAS..73..125E
ADC_Keywords: Positional data ; Clusters, open ; Regional catalog
Description:
The catalog contains the positions (equinox B1900.0 and epoch B1955.0)
of 502 stars in a region of about 1.5 degrees square in the Pleiades
cluster, centered on Eta Tau. These coordinates have been derived from
measurements of stellar images obtained with 65 exposures of various
durations on 14 photographic plates with two telescopes at McCormick
Observatory and Van Vleck Observatory. The plates were reduced by the
plate overlap method, which resulted in a high degree of systematic
accuracy in the final positions. Data in the machine version include
Hertzsprung number, color index, photovisual magnitude, right
ascension and declination and their standard errors, proper motion,
and differences between the present position and previous works.
Data for exposures, plates, and images measured, present in
the published catalog, are not included in the machine version.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 80 502 The catalogue (Tables III and IV of the paper)
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See also:
I/163 : US Naval Observatory Pleiades Catalog (van Flandern, 1969)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Hertzsprung Number in Hertzsprung's (1947) catalogue
5- 8 F4.2 mag CI Colour index
9- 14 F6.2 mag Ptm Photovisual magnitude
15- 16 I2 h RAh Right Ascension, Equinox=B1900, Epoch=1955.0
(hours)
18- 19 I2 min RAm Right Ascension B1900 (minutes)
21- 26 F6.3 s RAs Right Ascension B1900 (seconds)
28- 30 I3 0.1ms e_RAs Standard error on RA
31 A1 --- DE- Declination, Equinox=B1900, Epoch=1955.0
(sign)
32- 33 I2 deg DEd Declination B1900 (degrees)
35- 36 I2 arcmin DEm Declination B1900 (minutes)
38- 42 F5.2 arcsec DEs Declination B1900 (seconds)
43- 45 I3 mas e_DEs Standard error on DE
47- 50 F4.2 --- rmsRA r.m.s. value for RA (1)
52- 55 F4.2 --- rmsDE r.m.s. value for DE (1)
56- 59 I4 0.1mas/yr rpmRA ? Relative Proper motion in RA (2)
61- 64 I4 0.1mas/yr rpmDE ? Relative Proper motion in DE (2)
66- 68 I3 0.1mas/yr DrpmRA ? Difference in rpmRA with Hertzsprung (1947)
70- 72 I3 0.1mas/yr DrpmDE ? Difference in rpmDE with Hertzsprung (1947)
74- 76 I3 0.01arcsec DRA ? Difference in RA with Koenig (1924)
78- 80 I3 0.01arcsec DDE ? Difference in DE with Koenig (1924)
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Note (1): the r.m.s. values are defined by
rms = sqrt(Sum((o-c)2/sigma2)/(n-1))
where n is the number of plates,
(o-c) is the residual and
sigma the actual error of the measurements on each plate
A large rms value means therefore an agreement worse than expected on
the basis of the weighting of the individual measurements, and a small
rms an agreement better than expected.
The product e_RAs x rmsRA (resp. e_DEs x rmsDE) is then a good
approximation of the dispersion of the individual contributing
positions around their mean.
Note (2):
The values of the proper motions are not compatible with the FK4 system.
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References:
Hertzsprung E., 1947, Ann. Sterrew. Leiden 19, 1A =1947AnLei..19....0H 1947AnLei..19....0H
Koenig A., 1924, Astron. Nachr., 222, 177 =1924AN....222..177K 1924AN....222..177K
Historical Notes:
* The catalogue was received in 1978 from Dr J. Sibol; no attempt has
been made to verify the contents since the published catalogue was
published from a machine-readable data set.
The electronic catalogue was documented in 1979 by Theresa A. Nagy
for NASA Greenbelt (document R-SAW-7/79-32)
* 25-Sep-1995: Description added at ADC
* 02-Jan-1996: Documentation completed at CDS according to standards.
* 28-Dec-1999: Note (2) added from ADC version
(End) Francois Ochsenbein [CDS] 02-Jan-1996