RMS as a function of frequency in the spws covering the H₂O 183 GHz line imaged with a robust parameter of 0.0. Left: Spectra in topocentric coordinates. The telluric due to the water in the Earth’s atmosphere increases the noise at a velocity of 0 km s⁻¹. Right: Same spectra but in the local standard of rest frame. The number within brackets in the labels indicates the velocity width used for the bandpass calibration.