The variability of ST Leonis (70.1919; H. V. 3513) was discovered by Miss Cannon in 1919'). The first investigation of the features of its variability was made by Mr. S.
Beljawsky2), who found the following results: Max@ = 2424540.422 J. D. +Od477990.f? M -m =odo35. I My observations were carried out from December 1925 to May 1927 on the ))Mirowedrnijecc-Society Observatory (1926), and on the Observatory of the ].eningrad-University (1927). They were performed by means of two refractors with apertures of 175 mm and 2 2 5 mm, which belong to the uMirowedenijecc-and University-Observatory, respectively.
The following stars were used as comparison-stars. ' 11155 5,855 Mag. a = B I ) + 1 1 ~2 3 8 2 11~30m5 +11'23' o?o 9m3 11 = Anonyma 31.G -I I 2 0 4.4 9.8 k = )) 31.3 + 11 1 3 8.8 10.4 d= 0 30.5 + I I 24 12.7 10.8 e = )) 30.6 -I-I I 24 14.8 11.1 b = H 3 1 . 2 + I I 2 1 17.8 11.4
The observations usually were made by Pickering's method, but sometimes Argelandds method was used. From the estimates, I have obtained the step-scale of the brightness of the comparison-stars. This scale was reduced to the magnitude-scale of the Bonner Durchm~sterung~).
From my observations I have obtained the following five epochs of the individual-maxima, and of the moments, when the brightness of the star was equal to 10.5 steps (on the ascending branch of the light-curve).
M a x i m a.
Rrigntness Br. 10.-