Porrima is a binary with an orbit of 168.7 years. At the moment the stars are near to their closest approach and will be difficult to separate for the next few years. This gives an excellent oppertunity to observe real change in the separation and position angle of a double.
Both stars are of almost equal brightness: magn. 2.7 and 2.8 (Hipparcos 1997) or 3.5 and 3.6 (Tycho 2 2000) which makes them difficult to split when they are around or less than 1" separated, but which also makes the pair a brilliant double when their separation is larger again.

These images gives an indication, note that different sources give different values:


 I have observed Porrima the last few years, and it's becoming a real challenge:





May 2001


Reasonable seeing, just separated with 280x, easy with 560x

April 2002


Moderate seeing, snowman with 140x, indication with 185x, separated with 280x, easy with 400x 

May 2002


Moderate seeing, elongated with 180x, separated with 360x

March 2003


Less-than-moderate seeing, reasonably well separated with 280x


 Images and measurements by Steve Bodin, using a C8 and video-camera:


 The motion of Porrima, composite image from images of 2001, 2002 and 2003:


 Near minimum distance; the 2005 image: