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    24-Jul-2014
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1.5.2 Geographical and time coverage

Besides the self-calibration and the good vertical resolution, the advantage of the stellar occultation method is the excellent global coverage provided by the multitude of suitable star targets. A typical weekly coverage is shown in Figure 1.4 and Figure 1.5 (historic and recent maps can be found at  http://earth.esa.int/pcs/envisat/gomos/planning_maps). Until early January 2005, the daily number of measurements was about 400. The nominal measurements were then stopped, because of a failure in the telescope rallying drive. They resumed in July 2005, but with a reduced daily total number of measured occultations estimated to be about 280.

Figure 1.4: Example of geographical coverage of GOMOS measurements (measurements planned between 6 and 13 April 2004). The colour code for each occultation corresponds to the star ID.

Figure 1.5: Example of geographical coverage of GOMOS measurements (measurements planned between 7 and 14 April 2007). The colour code for each occultation corresponds to the star ID and its magnitude.

The variation of the latitude-longitude coverage with the obliquity for each occultation is illustrated in Figure 1.6 .

Figure 1.6: Area probed by occultations planned between 7 and 14 April 2007 and highlighted by occultation obliquity range.