Burnham: Measures of Proper Motion Stars 
The proper motion of the binary system is given : 
Auwers o"o64 in 88?2 
Boss 0.090 in 97.0 
The only other positions of the SD star are from the star 
catalogues: 
1825 334? 1 12579 Weisse 
1893 329.5 131-9 A. G. Wein 
The orbit of the close pair is wholly uncertain, and likely 
to remain so for a long time. A difference in the computed 
periods by the same authority of more than 500 years is evi¬ 
dence on this point. (See General Catalogue, p. 912.) 
10570. 
Espin 94. (6.5.. 
•9-5) 
R. A. 2o h 
45™ SU Deck + 
49° 4i' 
A and B 
1910.589 
I 3?02 
100'.'96 
.605 
12.93 
100 76 
.608 
12.81 
100.87 
1910.60 
12.92 
100.86 
B and C (10.0) 
1910.589 
8 i ?9 
2%2 
.605 
79-5 
2-39 
.608 
78.0 
2.65 
1910.60 
79.8 
2-5S 
The principal star has no sensible proper motion: 
Groombridge o7oo7 in 261 ?5 
10577. 02 (App.) 211. (6.5...7.2) 
R. A. 20” 46'" 24 s Deck + 58° 18' 
I9II-545 
263?04 
i°9?94 
•548 
262.73 
109.36 
.564 
263.OI 
109.30 
I9II-55 
262.93 
109.53 
The change appears to be due wholly to the proper motion of 
B. The star catalogues give A no sensible movement. These 
stars are respectively Groombridge 3309 and 3307. 
Measures 07171 in 6i?4 
Groombridge 0.169 in 58.2 
10586. H 1588. (9.6...11.6) 
R. A. 2o h 47 m 17 s Deck + 62° 30' 
1910.493 
33?8 
i8?78 
■ 509 
32.0 
18.46 
• 512 
32.4 
18.43 
1910.50 
32.7 
18.56 
No other measures. 
10587. Ho 145. (8.7...10.2) 
R. A. 20” 47 m 24 s Deck + 34 0 46' 
1907.329 
3i o?i 
9'.'oo 
•351 
310.7 
8.83 
•444 
310.4 
8.99 
1907.37 
310.4 
8-94 
Motion in angle and distance. From the four 
positions by 
Ho, Doo and |3 (1886-1911) the proper motion of A is: 
o'.'o 82 in 88?o 
10588. 
P 155- ( 6 . 5...7.4) 
R. A. 20 11 47' 
n 24 s Deck + 50° 58' 
AB and D (11.4) 
1909.515 
48?11 198724 
•534 
47.98 198.61 
•55i 
48.01 198.05 
I909-53 
48.03 198.30 
The first measures are 
uncertain in distance: 
1879.96 48!o8 
200791 in 
B1 
1881.43 48.37 
198.73 in 
B1 
10595. 
N 2734. (8.2...8.7) 
R. A. 2o h 48™ 21 s Deck + 12 0 39' 
I9H.545 
199)6 
24?79 
•564 
199.8 
24.69 
•567 
199-6 
24.50 
1911.56 
199.7 
24.66 
I have given the apparent proper motion of A (o'.'ni in 
i25?2) on the assumption that B is fixed, but as this is 8.7 m 
it might have some motion of its own. Unfortunately there is 
no faint star near enough for comparison. 
10609. 16 Delphini. H 1592. (5.6...12.2) 
R. A. 2o h 49 m 55 s Deck + 12 0 7' 
1909.496 
.512 
-515 
20?93 
20.13 
20.17 
38? 18 
38.14 
38.24 
1909.51 
20.41 
38.19 
1911-509 
2I?30 
37"9i 
.526 
20.39 
38.31 
•529 
20.03 
38.29 
1911-52 
20.57 
38.17 
The four (3 measures on 1311 (1879-1911) give for the proper 
motion of 16 Delphini: 
o".o 63 in 46?8 
The value derived from meridian positions is too small: 
Auwers 0^024 in 6s?6 
Boss 0.044 in 74.3 
265 
