Large velocity gradient models of the HC3N emission in Cha- MMS1 for different densities (filled cyan, blue, and green squares, as labeled). The four panels correspond to kinetic temperatures of 7.1, 8.5, 10.9, and 16 K, left to right, respectively. The open red circle shows our DSN observation while the red squares are SEST observations of Kon-tinen et al. (2000). The error bars correspond to a typical 20% absolute calibration uncertainty.