Left: line-of-sight velocity measured from the observed shift in wavelengths for the Hα and [O II] lines (see Tables 2 and 3). The x-axis corresponds to the projected radius on the major axis of the galaxy in the plane of sky. The thick horizontal and vertical dashed lines denote the V_sys and major axis of the galaxy, respectively. Right: rotation curve of Malin 1, projected on the plane of the galaxy. The red and black points indicate the Hα data and [O II] data, respectively. The green open circle shows the Lelli et al. (2010) H I data point in the same radial range. The region name of each point is inidcated with blue letters.