title: Measurement of the methyl cyanide E/A ratio in TMC-1.
abstract: We have observed the methyl cyanide (CH3CN) 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 NE/NA approximately 0.75 +/- 0.10.  The total methyl cyanide column density is Ntotal = 5 10(12) cm-2 toward TMC-1, in agreement with earlier results from the J=1-0 lines.
authors.affiliation: Korea Astronomy Observatory, Whaam-dong, Yusong, Korea.
authors.forename: Y C
authors.initials: YC
authors.lastname: Minh
authors.forename: W M
authors.initials: WM
authors.lastname: Irvine
authors.forename: M
authors.initials: M
authors.lastname: Ohishi
authors.forename: S
authors.initials: S
authors.lastname: Ishikawa
authors.forename: S
authors.initials: S
authors.lastname: Saito
authors.forename: N
authors.initials: N
authors.lastname: Kaifu
mesh_terms: D000097:Acetonitriles / Q000032:analysis*; D055580:Astronomical Phenomena; D001256:Astronomy; D005118:Extraterrestrial Environment; D016011:Normal Distribution; D013057:Spectrum Analysis
chemical_list: D000097:Acetonitriles; C032159:acetonitrile