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W. Collmar, V. Schönfelder, S. Zhang (MPE), H. Bloemen, W. Hermsen (SRON-Utrecht), J. Ryan (UNH), K. Bennett, O.R. Williams (SSD-ESA)
The COMPTEL experiment aboard the Compton Gamma-Ray Observatory (CGRO) pioneered the \gamma-ray sky in the 0.75 to 30~MeV band. It has detected 11 AGN emitting at these energies: 10 blazars and the radio galaxy Centaurus~A. The most significant one for COMPTEL is the blazar-type quasar 3C~273. In the sum of the first 6.5 years of the mission, the blazar is significantly detected in the standard COMPTEL bands above 1 MeV: ~10\sigma in the 1-3~MeV, ~10\sigma in the 3-10~MeV, and ~6\sigma in the 10-30~MeV bands. The fluxes in these bands indicate a curved time-averaged MeV spectrum, which has to change from a soft shape at high energies to a harder one at lower energies with an emission maximum somewhere between 3 and 10 MeV. Due to the significant detections in these 3 bands we currently analyse the COMPTEL data of 3C~273 in smaller energy windows (i.e., ~10 independent spectral points) to derive a best possible description of the spectral turnover in shape (e.g., smooth or sharp) and strength (e.g., amount of change in spectral index) occuring at MeV energies. This MeV spectrum, which will be the best resolved one of any AGN yet, will be presented, and its implications on the emission processes of \gamma-ray radiation in 3C~273 in particular and blazars in general will be discussed.