Poland's 1973 Copernicus commemorative program was one of the more elaborate the NBP had mounted to that point, timed to the 500th anniversary of the astronomer's birth. This trial strike in .625 silver sits outside the regular bullion and circulation issues — produced for approval and archive purposes rather than distribution — which explains why Fischer and Parchimowicz each catalog it separately from the standard Proof and circulation variants. The "big" designation distinguishes it from the smaller-diameter type struck in the same campaign.
Poland's 1973 Copernicus commemorative program was one of the more elaborate the NBP had mounted to that point, timed to the 500th anniversary of the astronomer's birth. This trial strike in .625 silver sits outside the regular bullion and circulation issues — produced for approval and archive purposes rather than distribution — which explains why Fischer and Parchimowicz each catalog it separately from the standard Proof and circulation variants. The "big" designation distinguishes it from the smaller-diameter type struck in the same campaign.