Velocity-integrated maps of the [CI](³PP₀) line emission (color scale and contours in panel a)), and the CO(J = 1−0) line emission of NGC 253 (color scale, panel b)). Panel c) shows the line ratio between the [CI] and CO emission in T_b scale (in color); to convert the line ratios from temperature scale into energy units (i.e., from K kms s^-1 for the intensities to W m^-2 sr^-1), it needs to be multiplied by a factor of ~80 (≡(ν_CI(1−0)/ν_CO(1−0))³). In all panels the contours represent [CI] line emission from panel a). Contours (and/or color steps) start from 40σ to 300σ in steps of 20σ(≡108 Jy/beam km s^-1 = 12 K km s^-1) for panel a), from 150σ to 1200σ in steps of 75σ(≡21.6 Jy/beam km s^-1 = 43 K km s^-1) for panel b) (color steps), and from 0.04 to 0.36 in steps of 0.02 for panel c) (color steps). The crossing of the dashed lines in each panel marks the center of NGC 253: RA = 00^h47^m33^s17 and Dec = −25°17′17.1′′. The synthesized beam is shown as a dashed ellipse in the lower left corner of each panel. The arrows in panel c) indicate the direction of the outflows seen in X-ray and Hα images (see, e.g., Bolatto et al. 2013).