CHAPTER XII. 
8518 Z CASSIOPEIA. ' ' 
R. A. 23I1 39m 39S.9; Dec. + 56° 1' 33" (1900). 
This variable was discovered by Anderson in 1898 and observations began 
in January, 1899. The field was measured with the micrometer on the 6-inch 
in January and February, 1899, but as the approximate place given for the star 
fell nearer to r than to the true place of the variable, that star was marked as 
the variable in the finding chart published by the writer in Popular Astronomy , 
7 , 94. The place of the variable given above was measured with the 6-inch from 
the stars a and b, which are given in the Helsingfors-Gotha A. G. catalogue. 
The stars b, d, n, and x were connected with the variable in January, 1900, with 
the 40-inch. 
My experience with this field is a good illustration of the advantage of using 
several standard magnitude stars. The list selected included B. D. -T54 0 3033, 
but after the photometer measures were completed it was found that the star had 
been misidentified, 3036 being measured instead. The measures were therefore 
reduced with the other two stars as standards, without much loss in accuracy. 
A few of the faint comparison stars are so close to the variable that the 
scale used for the other charts would be too small; this chart is therefore repro¬ 
duced on nearly double the usual scale. 
Table 99.—8518 Z Cassiopele. Standard Magnitude Stars. 
1900. 
Magnitude. 
Residuals. 
Star. 
B. D. No. 
R. A. 
Dec. 
Color 
P. DM. 
Catalogue. 
Measured. 
From 
Cats. 
3 
Nights 
inter 
se. 
H. C. 0 . 
P. DM. 
H. 
P. 
H. 
P. 
A 
O 
+ 55 3010 
h in s 
23 39 56 
O / 
+ 55 14-7 
WG 
6.48 
6.58 
6.76 
6.65 
+ 28 
+ 7 
±4 
D 
+ 55 2990 
23 32 26 
+ 55 19-4 
G 
7 - 5 i 
7.20 
7.24 
7 -13 
-27 
-7 
±5 
Mean.... 
7.00 
6.89 
7.00 
6.89 
±28 
±7 
+ 4 
Table ioo.-—Comparison Stars in B. D. Catalogue. 
Star. 
B. D. 
1855 - 
No. 
Mag. 
R. A. 
Dec. 
b 
O 
+ 55 3007 
9.2 
h m s 
23 37 5 
O 
+ 55 50 0 
a 
+ 55 3011 
8.6 
23 37 47 
+ 55 39-9 
161 
