1996A&A...314..909W

We present a map of the distribution of the J_Ka_Kc=1₀₁-0₀₀ transition of HNCO made with the 100 meter telescope at 21.981 GHz, with an angular resolution of 43". This line is found in emission over the entire region mapped. The emission region has a FWHP size of >2' in α by ∼3' in δ, with a peak ∼45" north of Sgr B2(N). We decompose the HNCO emission into three components: (1) A compact peak ∼45" almost exactly north of Sgr B2(N), (2) Blended with this peak is a weaker maximum centered on Sgr B2(N), and (3) More extended lower brightness emission arising from the envelope. The compact peak is centered at α=17h44m10.4, δ=-28d20'25" (1950.0). There, the relative abundance of HNCO to H₂ is >10^–8, a factor of >10 larger than elsewhere. The HNCO emission peak is not centered on any of the previously known molecular regions in Sgr B2. There are maxima of NH₃, HNO, HC₃N, and N₂O within ∼30" of the HNCO peak. This compact core is prominent in nitrogen-bearing species and in the 4_–1-3₀ line of CH₃OH, but is not an intense dust emission source. It appears that this region is less developed than Sgr B2(N), which has a large abundance of complex molecules.