The revised COMPTEL Orion results

COMPTEL observations of the Orion/Monoceros region have shown distinct evid ence for excessive 3-7 MeV emission that was attributed to nuclear de-excit ation lines from accelerated C-12 and O-16 nuclei. Unfortunately, we must c onclude now that this appears to be a spurious result. This conclusion foll ows from a better understanding of the instrumental background, from a bett er exposure of the region, and from an improved analysis method. We show he re how the impact of each of these gradually reduces the signal to a less t han 3 sigma result. The prime underlying cause seems to be Na-24 activation in and around:he upper COMPTEL detectors. Combining all available data, we now set a 2 sigma flux upper limit on the 3-7 MeV emission of Orion of 3 x 10(-5) gamma cm(-2) s(-1) to be compared with the previously derived flux of similar to 10(-4) gamma cm(-2) s(-1).