Vibrationally excited HC3N toward hot cores

We report IRAM 30-m observations of vibrationally excited rotational transi tions of HC3N toward a sample of six ultra-compact HII regions. In addition , Effelsberg 100-m and Plateau de Bun Interferometer measurements were cond ucted toward the region G10.47+0.03. We detected the upsilon(7) = 1 state o f cyanoacetylene toward all six regions and the upsilon(6) = 1 line toward five of them. Toward G10.47+0.03, we detected lines from 11 different vibra tionally excited states with excitation energies up to 1600 K above ground. Of these, six are first detections. We also have detected several transiti ons of C-13 substituted cyanoacetylene in the upsilon(6) = 1, upsilon(7) = 1, and upsilon(7) = 2 states and provide improved rest frequencies for seve ral of these. The population distribution of the vibrationally excited HC3N molecules is analyzed and it is concluded that our results are consistent with thermalised level populations at a temperature of 270 K. From the inte rferometer results we find the source of HC3N emission to be coincident wit h NH3(4,4) and CH3CN emission within the positional error of 1 " In an appendix, we report the first astronomical detection of lines from vi brationally excited HNCO in G10.47+0.03.