Forty-eight objects were detected in the 5(-1)(-4)0(E) methanol line at 83.
5 GHz during a survey of Class I maser sources. Narrow maser features were
found in 14 of these. Broad quasi-thermal lines were detected toward other
sources. One of the objects with narrow features at 84.5 GHz, the young bip
olar outflow L1157, was also observed in the 8(0)-7(1)A(+) line at 95.2 GHz
: a narrow line was detected at this frequency. Analysis showed that the br
oad lines are usually inverted. The quasi-thermal profiles imply that there
are no more than a few line opacities. These results confirm the plausibil
ity of models in which compact Class I masers appear in extended sources as
a result of a preferential velocity field. (C) 2001 MAIK "Nauka/Interperio
dica".