Maps of moments 0, 1, and 2 from left to right panel for ¹²CO J = 2 → 1 (upper row; this work) and ¹³CO J = 2 → 1 (lower row; Piétu et al. 2005). The white ellipse and arcs trace the best-fit dust ring and the identified CO spiral arms, respectively. Left panels: The contours start from and step in 0.12 Jy beam^-1 km s^-1. Middle panels: contours steps are 0.4 km s^-1. Right panels: contours steps are 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1.0, ... km s^-1. The unit of the wedge is Jy beam^-1 km s^-1 for moment 0 maps and is km s^-1 for moment 1 and moment 2 maps.