  We have used the NASA Tidbinbilla 70-m antenna to search for emission from
the 2(1)-3(0)E 19.9-GHz transition of methanol. The search was targeted towards
22 star formation regions which exhibit maser emission in the 107.0-GHz
3(1)-4(0)A+ methanol transition, as well as in the 6.6-GHz 5(1)-6(0)A+
transition characteristic of class II methanol maser sources. A total of 7
sources were detected in the 19.9-GHz transition, 6 of these being new
detections. Many of the new detections are weak (< 0.5 Jy), however, they
appear to be weak masers rather than thermal or quasi-thermal emission. We find
a strong correlation between sources which exhibit 19.9-GHz methanol masers and
those which both have the class II methanol masers projected against radio
continuum emission and have associated 6035-MHz OH masers. This suggests that
the 19.9-GHz methanol masers arise in very specific physical conditions,
probably associated with a particular evolutionary phase. In the model of
(Cragg, Sobolev & Godfrey 2002) these observations are consistent with gas
temperatures of 50 K, dust temperatures of 150-200 K and gas densities of
10^6.5-10^7.5 cm^-3.
