On the nature of the discrete gamma-ray sources in the vicinity of the supernova remnant G312.4-0.4

We discuss the excess gamma-ray emission seen from point sources in the vicinity of the supernova remnant (SNR) G312.4-0.4 with the EGRET instrument on board the Compton Gamma Ray Observatory in the energy range of 100 MeV to 10 GeV. Two gamma-ray sources have been significantly detected. The best-fit position for the source 2EG J1412-6211, which was originally discovered by COS B (catalog name 2CG 311-01), is located approximately 17' southwest of the center of the supernova remnant G312.4-0.4. We find the gamma-ray flux level of this source to be relatively constant over a period of 4 yr. The origin of the gamma-ray emission with respect to a SNR-pulsar source is discussed. The best-fit position for the other source, 2EGS J1418-6049, lies 1.degrees 3 northeast of the center of G312.4-0.4 It has a variable flux level, with a spectrum extending up to a few GeV. We argue that 2EGS J1418-6049 is transient in nature and that its variability makes it unlikely to be associated. with G312.4-0.4 or any other SNR or isolated pulsar. We suggest that this source may belong to a new class of unidentified Galactic sources which includes the EGRET source 2EG J0241 + 6119 (2CG 135+01).