Suisei Planitia [SEP] located on astronomical body
Suisei Planitia
Suisei Planitia is a large basin on Mercury. Ghost craters are unusual forms that occur in the Suisei Planitia. They are buried and rounded in profile, with only their rim crests rising above the surrounding smooth plains. It has been suggested that the smooth plains that Suisei Planitia is part of (Caloris Planitia) might be ejecta from Caloris that were melted by the impact. The name for this Planitia was approved in 1976. 
The "MESSENGER" Mercury orbiter crashed into the plain in April 30, 2015
area were blurred by spacecraft motion, and so reliable crater counts could not be obtained. However, smooth plains south of lat 65° N. in the Shakespeare quadrangle, in the crater Strindberg and in Suisei Planitia, are included in these counts. The plains materials that lie outside Borealis Planitia are distributed in irregular belts, which are subparallel to the terminator and to one another. Eastward from long 190° W., the following belt pattern is observed: intercrater plains material, intermediate plains material, and again intercrater plains material.