Science, Vol. 284, Iss. 5415, p. 794-798, Apr 1999.
Figure 1. Latitude-longitude map of one-third of the southern hemisphere of Mars. Subsatellite latitude and longitude for each periapsis are indicated by a largely north-south line segment representing that part of the orbit below 200-km altitude. The color of each segement represents the radial component of the magnetic field (Br) measured by MGS at that location without correction for the variation of satellite altitude (200 km < r < 103 km). The radial field component within the survey area ranged from -1389 nt (blue) to 1476 nt (red). A stretched color bar is used to partially compensate for altitude variation; this method of display emphasizes the sign of B, rather than the magnitude, which is strongly dependent ob distance from the source (26). Where two tracks overlap, the latest track, with a more southerly latitude of periapsis, appears over printed on the earlier track.