Torsionally excited methanol at 44.9 GHz

Abstract

Using the Haystack Observatory 37-m radio telescope we have undertaken a search for emission in the 2(0)-3(1)E rotational transition of methanol in its first torsionally excited state (v_t=1) at 44.9 GHz. We examined seven galactic sources -- six strong emitters of Class II methanol maser lines and Orion KL, the only source where this line had been previously detected. We confirm (at a level of 5\sigma) the previous detection and report two new detections -- a reliable (9\sigma) detection in W3(OH) and a marginal (3.5\sigma) detection in NGC 6334F. Upper limits for other sources are presented. Although we did not see obvious signatures of maser amplification in this transition in any source, arguments in favor of weak masing in W3(OH) are presented.