Seen here, the near perigee Full Moon still hugs the horizon, distorted by atmospheric refraction as it rises over Boston, Massachusetts, USA.

High frequency skywave over-the-horizon radar can provide a wide coverage beyond the horizon by means of refraction within the ionosphere.

The refraction effect on positioning of the over-the-horizon radar signal is analyzed. The charts of the refractive error(elevation error and range error) are also given.