In the present article we have decided to exclude the effect of response curves and to compare synthetic color indices of the Sun with synthetic color indices for a group of G2 V stars which were included in the Alma-ata spectrophotometric catalogue [6], and were selected by us earlier [5]. For the Sun we used data from a paper of Makarova et al. [7]. In that paper, the solar energy distribution was derived as a weighted mean from results of five investigations. The standard error of the energy distribution is equal to 1.5% in the ultraviolet and blue regions and decreases to 0.4% in the red.
Color indices of the Sun and stars were computed in four photometric systems (UBV, WBVR, uvby, [8], [9] and Vilnius, [4]) using the same stars in all systems. The result is that the Sun lies within of the G2 V area on all two-color diagrams. We think of that conclusion as being rather positive because only two basic quantities are compared in the case: solar energy distribution and the scale of the Alma-Ata spectrophotometric catalogue. Errors of an individual star energy distribution are quasi-random if a sample is rather extensive and increase a point scatter only without moving a central line. A hidden systematic error of the spectrophotometric catalogue [6] and errors of the solar energy distribution are apparently small, as it is impossible that they cancel each other to place the Sun near the central line.
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[5] Kniazeva,L.N., Kharitonov,A.V. 1994, Astronomicheskij Zhurnal (Russian), 71, 458.
[6] Kharitonov,A.V,. Tereshchenko,V.I., Kniazeva,L.N., 1988, Spectrofotometricheskij katalog zvezd (Stellar spectrophotometric catalogue), (Alma-Ata:"Nauka KazSSR" publishing house).
[7] Makarova,E.A., Kazachevskaya,T.V., Kharitonov,A.V. 1994, Solar Phys, 152, 195.
[8] Hauck,B., Mermilliod,M. 1990, uvby-beta Photoelectric Photometric Catalogue}, Computer-readable version.
[9] Kodaira,K., 1975. Problems in Stellar Atmospheres and Envelopes}, p. 155.