Forthcoming 2005 Mars
The SPC on Grids at λ=235°Ls, 250°Ls, 270°Ls
Masami MURAKAMI and Akinori NISHITA
he spc has hitherto indicated the Martian south pole, but since around λ=235°Ls its center moves to the direction of Ω=030°W, and so it is not so easy to point out the pole direction hereafter. To exactly know the axis it is advisable to record on the image frame the direction of the planet moving out when the motor drive is made stopped (as usually done by Don PARKER and Yukio MORITA). Here we show the schematic diagrams of the spc how it is seen deviated from the pole at particular angles at λ=250°Ls and λ=270°Ls. As to the form and size of the spc (especially at λ=250°Ls) we referred to the results of the Lowell Observatory, the Viking data and recent MGS-MOC images.
NB: The indication p shows the preceding direction of the movement of the image when the motor drive is stopped. We depict also the noon line (N-line) by a dotted line. This shows how we mostly observe the afternoon side at present. The intersection of the N-line with another dotted line (M-line) is the point where the Sun shines at zenith (sub-Solar point DS).