338 
PRELIMINARY GENERAL CATALOGUE OF STARS FOR 1900 
REMARKS UPON THE TABLES OF SYSTEMATIC CORRECTIONS 
AND WEIGHTS. 
(1) Bradley 1755. The term in Aa a , depending on tg8, applies north of declination + 6o°, and 
it is necessarily very uncertain. 
(2) Pulkowa 1855. The observations upon which this Catalogue is based extend over a long 
period, and were chiefly made in broad zones. The mean Aa a applicable to the entire Catalogue 
is not far from +?oo7. Taking the Catalogue by zones, the following corrections have been 
determined, and may be substituted for the uniform correction + ^007. 
1 
K> 
O 
0 
pf 
0 
0 
0 
o° to +30° 
+30° to +6o° 
-f 6o° 
to Pole 
h 
S 
S 
S 
S 
S 
O 
+ .006 
.000 
— .004 
+ .007 
+ .012 tg 5 
I 
+ .009 
.000 
-.003 
+ .007 
+ .010 
2 
+ .013 
+ .001 
— .001 
+ .007 
+ .010 
3 
+ .016 
+ .001 
+ •003 
+ .007 
+ .010 
4 
+ .018 
+ .002 
+ .009 
+ .007 
+ .011 
5 
+ .020 
+ .004 
+ .017 
+ .007 
+ .010 
6 
+ .020 
+ .006 
+ .020 
+ .007 
+ .007 
7 
+ .020 
+ .007 
4 - .020 
+ .007 
+ .004 
8 
+ .019 
+ .009 
+ .016 
+ .007 
— .001 
9 
+ .017 
+ .011 
+ .011 
+ .007 
-.005 
10 
+ .015 
+ .012 
+ .006 
+ .007 
— .009 
11 
+ .012 
+ .013 
+ .003 
+ .007 
-.013 
12 
+ .008 
+ .014 
+ .005 
+ .007 
-.015 
13 
+ .005 
+ .014 
+ .010 
+ .007 
— .017 
14 
+ .001 
+ •013 
+ .015 
+ .007 
— .018 
iS 
—.002 
+ .013 
+ .016 
+ .007 
— .019 
16 
— .004 
+ .012 
+ .013 
+ .007 
— .020 
17 
— .006 
+ .010 
+ .008 
+ .007 
— .020 
18 
— .006 
+ .008 
+ .001 
+ .007 
— .016 
19 
— .006 
+ .007 
—.004 
+ .007 
— .006 
20 
-.005 
+ .005 
— .006 
+ .007 
+ .010 
21 
-.003 
+ .003 
— .007 
+ .007 
+ .019 
22 
— .001 
+ .002 
— .007 
+ .007 
+ .021 
23 
+ .002 
+ .001 
— .006 
+ .007 
+ .017 
24 
+ .006 
.000 
-.005 
+ .007 
+ .012 
(3) Pulkowa 75. The second term multiplied by “k” is computed under the hypothesis of a 
systematic error in adopted collimation, varying with the time of year (or with the temperature). 
The form of such a correction would be: 
(a sin a 4- b cos a) 
i-tg- 
2 
i-tg— 
wherein P is the polar distance, and the unit factor corresponds to 45 0 of declination. The result 
of computation gives: 
f — foi7 sin a -f foi3 cosa 
l — .c 
.002 sin 2 a + .006 COS 2 a 
k, 
I-tg 7 
45' 
wherein k 
