We present an analysis of COMPTEL observations made between November 1991 and
May 1994 of 2CG 135+01, a bright gamma-ray source located near the Galactic
plane. At energies above 1 MeV, an excess consistent with the position of 2CG
135+01 is detected in the sum of the observations, at flux levels which are a
factor of 10-100 below those published in the past. The detection significance
of this excess, when the possible presence of underlying Galactic diffuse
emission is neglected, is 6.6 sigma for 3 degrees of freedom. The differential
photon spectrum in the 1-30 MeV energy range can be described by a power law
with a spectral index of $1.95^{+0.2}_{-0.3}$. Due to the uncertainties
involved in modelling the Galactic-disk diffuse emission underneath the source,
the absolute flux levels must be considered uncertain by a factor of two. They
are consistent with the extrapolation of the time-averaged spectrum of 2CG
135+01 measured with EGRET, thereby strengthening the identification. No
significant temporal correlation between the gamma-ray emission and the
monitored radio emission of the possible counterpart radio source GT 0236+610
(showing a 26.5 day modulation) is found.
