Institute of Astronomy, Sofia, Bulgaria
The general idea is presented of the astrometric experiment " Rozhen-90": stars positions to be determined directly in a system of minimum three optical counterparts of the radio sources. For this purpose the especially suitable 2-m RC telescope of Rozhen Observatory was used and a mosaic of plates was taken covering an area of 1,5*1,5 Degree. The overlap of the plates is about 20 - 30 %. For an estimation of the proposed method possibilities, a detailed accuracy investigation is included.