Astronomical Applications Department, U.S. Naval Observatory pm AAS poster Page 9
TYCHIP Proper Motion Differences (for Individual Stars)
Distribution of Tycho-2 minus Hipparcos differences in proper motion for the individual stars in the selected subset of 162
double systems. The distributions are wider for the B components than for A, probably because the B components are on
average about one magnitude fainter. These distributions are significantly broader than those for the 98,909 stars in common
in the two catalogs that are not known to be members of double systems. The evidently poorer quality of the data for the
doubles may be related to Hipparcos satellite observational difficulties when more than one bright star was in the field of
view.
-40
-30
-20
-10
0
10
20
30
TYC-HIP Proper Motion (m as /yr)
0
10
20
30
40
50
60
70
N
u
m
b
er
of
S
t
a
r
s
Right Ascens ion (A com ponents)
Decl ination (A com ponents)
Right As cension (B com ponents)
Declinati on (B com ponents)
RMS A (RA) = 4 .35 mas/ yr
RMS A (De c) = 3 .30 mas/yr
RMS B (RA) = 6 .47 mas/ yr
RMS B (De c) = 5 .77 mas/yr
