Authors: S. Koyama, M. Kino, A. Doi, E. Ros, K. Niinuma, H. Nagai, K. Hada, M. Giroletti, G. Giovannini, M. Orienti
Journal: Transactions of IAA RAS vol. 40
Keywords: VLBI, Astrometry, Blazars
We report astrometric results on the stability of the core in the nearby TeV blazar Mrk 501 based on 6-epoch monitoring with the VLBA at 43 GHz. Our results suggest a stable position of the core within 98 ± 73 µas, refining our earlier findings by VERA in 2011, which pinpointed the position within 200 µas. We constrain bulk Lorentz factors of the jet based on the results of core position measurements. We will further discuss a possible relation between the source activity and the distributed scale of the radio core position.