33 379 



The double star BD + 22°536 iound by Trümpler (Publ. Astr. Soc. of the Paci- 

 fic 33, 270; 1921) is just outside the field investigated in the present paper. 



1 7. General Catalogue. 



In the general catalogue given at the end of this paper all the results have 

 been collected. It contains 1246 stars arranged according to their right ascension. 

 Several objects, too faint for accurate determination of their effective wavelength 

 have been included mainly to show the limit of the reliability of the results. For 

 these faint stars the general catalogue has merely the character of a Durch- 

 musterung. 



The first column gives the current number of the star. In order to facilitate 

 the identification of components of double stars, these have been marked: (comp. 

 Table 15). Known double stars not recognized as such in the present paper have 

 been marked with an asterisk *. The next three columns give the star numbers 

 according to Wolf (Ann. de I'obs. de Paris, Mém. Vol. 14, II, p. A 9; 1877), Gaul- 

 tier (Bull, de la Soc. astron. de France, Vol. 14, 445; 1900) and Graff (Astron. 

 Abb. der Hamburger Sternw. zu Bergedorf, Bd. 2, Nr. 3; 1920). The fifth and the 

 sixth columns give the right ascension and the declination for 1900, and the seventh 

 column the number of plates on which the position is based. The eighth column 

 gives the approximate photographic magnitude, which is only meant to serve for 

 identification purposes, and the ninth column the number of plates used in evalu- 

 ating the magnitude. The tenth and eleventh columns give the mean colour index 

 /; and its weight, the mean error of // being the square root of its reciprocal 

 weight. In the twelfth column the colour index of Shapley and Richmond (Contrib. 

 from the Mount Wilson obs. No. 218, Ap. J. 54, 323; 1921), converted into the scale 

 of /;, is given for comparison. The relation between Ii and the colour index of 

 Shapley and Richmond was found to be as follows 



ni 



7, S/î and R — -20 "20 "40 "OO "80 fOO 1-20 r40 TOO fSO 2-00 2-20 

 /; —•34 — -12 -10 -32 -54 "77 98 V\l r34 r49 r64 179 r94 



The weight of the /;_ values of Shapley and Richmond is found to be 20 m~"^ 

 corresponding to a mean error of ± ™'22. In deriving this mean error, systematic 

 differences, which seem to be present between different regions of the field, have 

 been disregarded. The most noticeable differences between the colour indices of 

 Shapley and Richmond and the effective wavelengths are shown by the stars no. 285 

 and 925. Especially for the fainter stars, where the weight of I^ as derived from 

 the effective wavelengths is small, the colour indices of Shapley and Richmond form 

 a welcome supplement. A comparison for the fainter stars of the two 7^ values in 

 the tenth and the twelfth column tends to show, that the small weights of the 7^ 

 values as derived from the effective wavelengths are somewhat greater than indic- 



1>. K. U. Vidensk. Selsk. Ski-., natiiiv. og niiiliiem. Afd,. S. Uickke. IV, 4. jq 



