1999A&A...343..801M

We observed SgrA* at 1.3cm on 1992 November 8 with a 14 station VLBI array and, using data from 10 of these stations, obtained a high-dynamic range image with a beam of 3.35x1.7milliarcseconds in position angle14°. The observed surface brightness distribution of SgrA* is best modelled by an elliptically shaped gaussian component with parameter values: flux density 1.05±0.10Jy, major axis of FWHM2.67±0.15milliarcseconds in position angle79°±10°, and axial ratio0.61±0.12, which are almost the same as the estimates of Alberdi et al. (1993A&A...277L...1A). We found no evidence of changes in the source structure of SgrA* among four sets of 1.3cm VLBI observations spanning almost a decade. It seems reasonable to conclude that both the emission of SgrA* itself and the surrounding medium acting as a refractive screen have reasonably constant relative orientation, emission rates and structures.