Astronomical Applications Department, U.S. Naval Observatory pm AAS poster Page 5
Example #1 of significant proper motion differences between Hipparcos and Tycho-2 resolved by
means of WDS data.
Projection of relative motion of the components of the double star system HIP 41953 + HIP 41955
in right ascension (left) and declination (right). The projection derived from Hipparcos proper
motions is shown as three green solid lines, with the nominal projection as the middle line, and plus
and minus one-sigma lines on either side. The comparable Tycho-2 projection is shown as three
dotted blue lines. The WDS observational measures, converted from separation and position angle
to differences in RA and Dec, are shown as red crosses.