Astrometric offsets for four different water masers with respect to the quasars used as reference position: J0613+1306 in the left plots and J0619+1454 in the right plots. The proper motions were subtracted from the parallax signatures. The solid and dashed lines represent the eastward (α cos δ) and northward (δ) individual fitting listed in Table 3, respectively. The Northward offset (δ) was shifted +0.6 mas for visualization purposes.