Visibility amplitude vs. JVLA baseline length for the brightest maser channel (at V_LSR = 6.43 km s^-1). The blue dotted and red dashed lines show the Gaussian fits to the amplitude profile using only data with baseline lengths lower and higher than 235 Kλ, respectively, which is the maximum baseline sampled with the B-Array. The amplitude and FWHM size of the fitted Gaussians are reported with consistent colors.