CHAPTER II.—T ANDROMEDA. 
17 
the mean zenith distance of the three standard stars was less than that of 
the measured stars. At zenith distance 21 0 a difference of corresponds to a 
change of 0.001 magnitude in the atmospheric absorption, which is negligible. 
The stars measured with the 12- and 40-inch were all within 20' of the variable, so 
that the correction would be even less. The subscript a 1, appended to the star 
letter, shows that the star was measured through one shade glass, which increases 
the magnitude numerically by 0.75 for the 6-inch and 0.84 for the 12- and 40-inch 
measures. 
Table 9.—103 T Andromeda. Constants for Reduction and Comparison with Catalogue 
Magnitudes . 
6-INCH. 
Star. 
A 
B 
a 
Means. 
M 0 .. . • 
October 15. 
October 27. 
October 30. 
C. 
Obs. Mag. 
A Mag. 
C. 
Obs. Mag. 
A Mag. 
C. 
Obs. Mag. 
A Mag. 
H. 
P 
H. 
P. 
H. 
P. 
H. 
P. 
H. 
P. 
H. 
P 
IT . 
0.84 
0.63 
1.16 
7 65 
7-44 
7-97 
7-73 
7-52 
8.05 
— .02 
+ .23 
- -23 
- 03 
+ . 10 
- 07 
0.44 
0.30 
0.76 
7 63 
7-49 
7-95 
7.71 
7-57 
8.03 
- .04 
4- .28 
- -25 
;° 5 
+ ■ 15 
-.09 
0-43 
0-37 
0.90 
7-55 
7-49 
8.02 
7-63 
7-57 
8. 10 
— . 12 
-|- . 28 
- . 18 
- -i 3 
+ • *5 
— .02 
0.88 
7.69 
6.81 
7-77 
6.89 
± . 16 
± .07 
0.50 
7.69 
7.19 
7-77 
7.27 
± . 19 
± . 10 
0-57 
7.69 
7.12 
1-11 
7.20 
± -19 
± • 10 
12-INCH. 
Star. 
c. 
d. 
Mean C . 
Mean Mag. 
Mo. 
Mag. 
6-inch. 
8.81 
9-33 
9.22 
9.12 
C. 
Sept. 11. 
0.88 
i -43 
1.07 
1-13 
9.12 
7-99 
Oct. 31. 
o 19 
1.12 
o. 76 
0.69 
9.12 
8-43 
Nov. 2. 
1.27 
215 
1.74 
1.72 
9.12 
7.40 
40-INCH. 
Star. 
Mag. 
12-inch. 
C. 
Jan. 14. 
Jan. 28. 
Feb. 25. 
k . 
11.85 
2.96 
1.83 
i -75 
t . 
11.66 
3.00 
1.74 
1.89 
x . 
13.12 
4-13 
2.79 
3.00 
Mean C.. . 
3-36 
2.12 
2.21 
Mean Mag. 
12.21 
12.21 
12.21 
12.21 
M 0 . 
8.85 
10.09 
10.00 
Table 9 contains the values of C, the reading from the absorption-curve of 
the wedge. From the mean C we derive the M 0 used in the reductions. In the 
first part of the table (6-inch) the observed magnitudes of the three standard stars 
are given, both in the Harvard and Potsdam systems, in the columns headed H. 
and P. Subtracting the catalogue magnitudes in Table 5 from these observed 
values gives the residuals tabulated under “A Mag.” for each system. The con¬ 
clusions which may be drawn from these residuals are discussed in Chapter XIV. As 
the measures with the 12-inch are based on the standards fixed with the 6-inch, 
the second division of the table contains the 6-inch magnitudes of the three 
standard stars b, c , and d, from Table 10, and the values of C found on the three 
nights with the resulting values of M 0 . Similarly the 40-inch division of the 
table gives the magnitudes derived with the 12-inch for k, t, and x, with C and 
M 0 . In the last two divisions the magnitudes are given in the Harvard system 
only, to express them in the Potsdam system add 0.08 as shown in Table 5. 
