CO rotational diagrams showing the column density per statistical weight versus the energy of the upper level. (a) The CO rotational diagrams measured at fifteen different positions throughout the warm extended envelope of Sgr B2, limited by the highest T_rot ~ 84 K (red line) and the lowest T_rot ~ 50 K (blue line). The coordinates and the T_rot of each diagram are given in Table 2. The CO line intensities throughout the envelope are not corrected for dust extinction. The CO rotational diagrams of Sgr B2(M) (b) and Sgr B2(N) (c) are calculated without extinction correction (dashed line), assuming that gas and dust are well mixed (continuum line) and that the CO emission is arising from the innermost region (dotted line). The diagrams suggest the presence of two temperature components, a warm gas component relative to the extended envelope (blue) and a hot gas component associated with the sources themselves (red).