Results of joint project on linking optical-radio reference frames

Abstract

Results of international co-operation between observatories from China, Russia, Turkey, and Ukraine on refinement of linking optical and radio reference frames are discussed. About 300 fields around extragalactic radio sources in the selected fields of extragalactic radio sources from −40 to +70 degrees in declination were observed with CCD ground-based telescopes. The catalogue of optical positions of more than 200 ERS with average accuracy 30 mas in ICRF by using of secondary reference stars from the UCAC2 and USNO-B1.0 catalogues was obtained as a result of this cooperation. The intermediate internal estimation of link between optical and radio reference frames was shown the angle values near zero within an accuracy of about 6 mas by using of secondary reference stars from UCAC2. A comparison of presented results with those of other investigations was made.