MEASUREMENT OF THE METHYL CYANIDE E/A RATIO IN TMC-1

We have observed the methyl cyanide (CH 3 CN) J=2−1 K=0 and 1 transitions toward the cyanopolyyne peak of TMC-1 and have derived an E/A (ortho/para) abundance ratio N E /N A ∼0.75±0.10. The total methyl cyanide column density is N total =5 10 12 cm −2 toward TMC-1, in agreement with earlier results from the J=1-0 lines