This is the "astronautical" convention adopted by the International Astronomical Union in the late 1960s, so that an astronaut standing on a moon or planet will see the Sun rise in the "east." But astronomers generally put south at the top, as normally seen in an inverting telescope
, and called celestial east on the sky "east" on a planet too, though this is astronautical west.
Unlike the view in an inverting telescope
, when you want to center an object that appears to the left in Sky Window's field of view, you swing the mount to the left.
(This direction will appear correctly in binoculars, backward in an inverting telescope
.) Our criterion was that a double be reasonably sure of resolution in a 2.4-inch telescope at medium powers.