Fig. 4.
Phase-referencing images of H2O maser spots at vLSR = 46.4, 43.9, and 42.0 km s−1. The contours are plotted at the level of σrms × 5 × √2n (n = 1, 2, 3, …). The peak intensity, Ipeak, and the rms noise level, σrms, are shown in the bottom left corner of each panel by Ipeak ± σrms.