Left panel: a picture of the W51A region extracted from Ginsburg et al. (2017). Its background is made of millimeter emission of lines and continuum from ALMA observations: HC₃N 24–23 in purple, C¹⁸O 2–1 in blue, CH₃OH 4₂–3₁ in orange, 1.3 mm continuum in green. Right panel: the dots in blue, red, and green represent the overall distributions of the H₂O, NH₃(9,6), and CH₃OH 4₂–4₁ masers in W51A, overlaid on the gray K-band continuum background detected in our VLA observation.