A preliminary control net of Mars.

A control net for Mars has been computed from measurements of 112 points identified on the Mariner 6 and 7 pictures, and areocentric coordinates of these points are presented. The coordinates of an initial point are determined, and the near-encounter frames of Mariner 6 and the adjoining near-encounter frames of Mariner 7 are tied to this initial point; then the far-encounter pictures of Mariner 6 and 7 are joined to the near-encounter pictures. The near-encounter Mariner 7 polar pass is located without reference to the far-encounter frames.