The COMPTEL experiment aboard the Compton Gamma Ray Observatory, sensitive in the energy range from about 0.7 to 30 MeV, observed the high-latitude region containing 3C 273 and 3C 279 during a 2-week period in June, 1991. A search for sources using a maximum likelihood analysis revealed two statistically significant point-like excesses, the positions of which are consistent with those of 3C 273 and 3C 279. These sources are the first QSOs detected at MeV energies. In the COMPTEL energy domain their spectra appear to be greatly different. A comparison with earlier and simultaneous measurements in neighboring energy ranges indicates that 3C 273 reaches its maximum luminosity at a few MeV while 3C 279 remains at tis maximum level from about 10 MeV up to a few GeV.
Astronomy and Astrophysics Supplement Series
European Southern Observatory (ESO)
W. Hermsen, H.J.M. Aarts, K. Bennett, H. Bloemen, H. de Boer, W. Collmar, A. Connors, R. Diehl, R. van Dijk, J.W. den Herder, L. Kuiper, G.G. Lichti, J. Lockwood, J. Macri, M. McConnell, D. Morris, R. Much, J.M. Ryan, V. Schönfelder, G. Simpson, H. Steinle, A.W. Strong, B.N. Swanenburg, C. de Vries, W. Webber, and C. Winkler. COMPTEL detections of the quasars 3C 273 and 3C 279. 1993, Astron. Astrophys. Suppl., v. 97, no. 1, pp. 97-100.