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Issue A&A Volume 416, Number 2, March III 2004 Page(s) 641 - 646 Section Stellar structure and evolution DOI 10.1051/0004-6361:20031730

A&A 416, 641-646 (2004)
DOI: 10.1051/0004-6361:20031730

Survey of long-term variability of stars

I. Reliability of magnitudes in old star catalogues

T. Fujiwara¹, H. Yamaoka² and S. J. Miyoshi<sup>1

1</sup>  Department of Physics, Graduate School of Science, Kyoto Sangyo University, Kamigamo Motoyama, Kita-ku, Kyoto 603-8555, Japan
    e-mail: sjm@gold.ocn.ne.jp
²  Department of Physics, Faculty of Science, Kyushu University, 4-2-1, Ropponmatsu, Chuo-ku, Fukuoka 810-8560, Japan
    e-mail: yamaoka@rc.kyushu-u.ac.jp

(Received 2 June 2003 / Accepted 30 September 2003 )

Abstract
The comparison of visual magnitudes of stars compiled in old catalogues is expected to yield information about their long-term magnitude variations. In seven old catalogues whose historical data have been intensively compared, 2123 sampled stars have been studied, disregarding stars that we could not identify, double stars which could be misidentified, or stars observed under poor conditions, and known variable stars with large amplitude discrepancies. The independence of stellar magnitude catalogues is demonstrated by comparing seven old studies to each other, suggesting that the magnitude estimates in each catalogue reflect the brightness at each observational period. Furthermore, by comparing them with a modern star catalogue, the magnitude differences show a Gaussian distribution. Therefore, if they are sufficiently larger than the deduced standard deviations, the magnitude variations between the catalogues can be considered real. Thus, the stellar magnitudes compiled in old studies can be used as scientific data within the average intrinsic uncertainty. These seven old catalogues can be used as data for the survey of the long-term variability of stars.

Key words: stars: general -- stars: variables: general -- catalogs

Offprint request: T. Fujiwara, tomochan@fuujin.kyoto-su.ac.jp

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