EGP/AJISAI

EGP (Experimental Geodetic Payload), also known as EGS (Experimental Geodetic Satellite) or Ajisai (Hydrangea flower), was launched on the first test flight of the H-1 rocket in August 1986. EGP is a sphere with a diameter of seven feet, and is covered with mirrors and corner-cube reflectors. The latter are used to reflect laser beams and are invisible to amateur observers, but the mirrors are spectacular. They are designed to reflect sunlight so the satellite can be photographed by ground stations for precise geodetic surveying measurements. The glints are probably in the third magnitude range but are visible to the naked eye only in very dark skies under good conditions. The brief flashes are too short to be noticed by the naked eye. In binoculars EGP resembles the strobe of an airplane but the flash pattern is more complex than a strobe light. Because of the extremely high orbital altitude of 1,500 kilometers, EGP is often visible closer to midnight than other satellites, and can frequently be seen on as many as four orbits during a single overnight observing session.