S21 - World Space Week Catalog Numbers

I just received an email from one of our correspondents that Scott finally released the catalog numbers for the World Space Week personalized stamp sheet back in late January. They are Vienna 404-408. So, if we believe that there are only 6,000 sheets available, once again we have some very rare United Nations stamps. Only 12,000 possible sets might exist. I'm eagerly awaiting the announcements from UNPA (supposedly in this quarter) that will let us know the printing quantities.