Observations of radio stars at the Valinhos CCD Meridian Circle

We present the astrometric results from the optical observation of 16 stars from the list of Wendker (1995), with detected or suspected radio emission . The results are given an the Hipparcos/Tycho reference frame. The stars a re evenly distributed in right ascension and the declinations range from -1 5.6 degrees to +28.6 degrees. This distribution, also allowed to obtain pos itions relative to the Twin Astrographic Catalogue (TAC 1.0). The observations were carried out with the Valinhos CCD Meridian Circle, in Brazil, operating in drift scanning mode. The average positional precision is at 40 mas and generally below 2 mas/yr for proper motions, obtained wit h the new reductions of the Astrographic Catalogue AC2000, as first epoch. In the strips taken from the observation of the 16 radio stars, 573 Tycho s tars, 545 ACT stars and 566 TAC stars were found. The analysis of the indep endent reductions made relatively to those frames and the large number of c ommon stars enables to focus on the equatorial zone, as represented by the three catalogues. As a result, the quality of Valinhos observations with re gard to ACT and TAC internal accuracies is verified(1).