45 

 Messier 11. 



N.G.C. 6705; «,,.„ = 18/' 45'".7, d„.„ = - 6°23'. 6 = - 4°, 

 / = 355° ; class : C3 '). 



W. Stratonoff. Amas stellaire de réoii de Sobieski (Messier 11), 

 Publ. de rObserv. de Taclikeiit N". 1, 1899. 



The catalogue contains 8()l stars. From the estimates and measu- 

 rements of diameters the magnitudes have been derived by means 

 of the Southern B. D. 



H. SiiAPLF.Y, Studies etc. IV. The galactic cluster iMessier 11, 

 Contrib. Mt. Wilson Observ. N". 126, 1916 (A. P. J. Vol. 45, 1917). 



For 458 stars the {)hotogr. and photovis. magnitudes have been 

 determined. For statistical research 364 stars were available, after 

 the uncertain magnitudes and the stars upon which the EuKKHARn- 

 effect ma}^ be of influence had been excluded. 



We tell off Stratonoff's catalogue and we determine the quotients 



A 4-1 



" -. It then appears that the magnitudes are too inaccurate and 



cannot be used. 



Now we reduce Stratonoff's magnitudes to Shapi.ey's scale. In 

 order to do so we compare the magnitudes of 293 stars. The results 

 are given in the table subjoined. 



Afterwards we determine by interpolation A,n for the corrected 

 magnitudes. In this way we (ind for the parallax from 2 determinations: 

 rr = 0".00055 rb 0".00ü03 



1) Shapley reckons Messier 1 1 among tlie open clusters. 



