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Tom says that typical sag of sonic booms results in 1 to 2 degree tilts, which . And that tilt would be 180 degees degrees different in azimuth from the above values.
These tilts appear to be due to the slope of the terrain, which is downward in the -u direction, in the direction that the sonic boom points. If the terrain was not sloping, these would be indicate a "backwards" boom tilt, i.e. the booms not drooping angling upward from the tower but angling upward. They generally agree on an approximate 5 degree slope of the terrain relative to the sonics, except the 9.9 degree tilt for the 7m sonic in Aug 2011.
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