With the Coverage button you can check the spread of the data directions, ie, how well they cover all possible directions.
The map represents the solid angle. The equator corresponds to direction at zero inclination, the upper pole is +90 and the lower pole -90. The mid vertical line corresponds to azimuth 0. East directions are on the right side, west ones on the left side. White spots represent directions of poor coverage. The whiter the worse.
The map of the coverage does not include data with the Skip flag.
Calibration
Table
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Computation