R.A. and decl. offsets of Sgr A* detections (points with errorbars) and of nearby star detections (symbols marked with names) relative to the predicted position of Sgr A* ((0, 0)). Different colors show the corresponding epochs. The inset panel zooms into the central part of the region. The gray solid circle marks the search radius of 10 mas (see Section 3.5) used to extract Sgr A* from the source list. The gray dashed circle shows the source confusion region (radius of 40 mas) within which nearby stars would cause bias and misdetection. We have removed confused Sgr A* detections and all nearby stars within this region in the inset panel. Overall, 13 detections of Sgr A* are free of source bias and used in this study.