Figure vsg.5 : Flight and VSG Period Properties. Each facet is represented as a point plotted in period parameter space: the average period and the period variation. Here the rms period variation, dp/p, is inverted to obtain the "facet resolving power" = 1./(2.35*dp/p); e.g., dp/p of 180 ppm is a facet resolving power of 2364. The 10 VSGs plotted here cover a region representative of the flight gratings. Four VSGs (HD2334, HA2045, MC1212, ME1408) have large non-flight-like periods and do not show on the plot.