1996A&A...307..209W

The first astronomical measurements of the J_k=12₂-12₁, 14₂-14₁, 15₂-15₁, 16₂-16₁, and 17₂-17₁ transitions of E type methanol are presented. Corrections to the line rest frequencies are significant. A map of the averaged J=15 to 17 lines shows that the emission arises from a region of 35"(δ) by ∼20"(α) FWHP size, centered ∼7" south, <2" west of the Hot Core. This is the Methanol Emission Center; the most intense CH₃OH masers are 15" to the NW. The J≥12 profiles are adequately fitted with two gaussian velocity components with FWHP {DELTA}v_1/2≃0.8km/s and ≃3km/s. For the wider component, our data give a rotational temperature of ∼100K. Excitation calculations indicate that the J₂-J₁ populations are inverted; the narrow velocity component in the J=15 to 17 transitions may be a low gain maser.