ROSAT OBSERVATIONS OF THE SIGMA SOURCE GRS-1227-273(025 NEAR 3C)

In an observation in the 40-80 keV band with the SIGMA instrument on t he Russian GRANAT satellite in which the quasar 3C 273 was not detecte d at > 2.5 sigma significance, another source, GRS 1227 + 025, was det ected at 5.5 sigma significance close to the position of 3C 273. If GR S 1227 + 025 is a separate source to 3C 273, then its presence will ca use confusion in the determination of the flux at high energies of 3C 273, which is one of the most widely observed extragalactic objects an d the testbed for many theories of active galactic nuclei (AGN). The r eality of GRS 1227 + 025 as a separate source to 3C 273 would be stren gthened if a realistic counterpart could be found in other high-energy observations. We have therefore searched a very deep ROSAT Position S ensitive Proportional Counter (PSPC) observation (0.1-2.4 keV) in whic h 3C 273 is the dominant source and have discovered three very faint s ources in the SIGMA error circle of GRS 1227 + 025, one of which corre sponds to a previously suggested counterpart found in observations wit h the Einstein observatory. However, X-ray spectral and timing analysi s shows that none of these is a likely identification of GRS 1227 + 02 5. We conclude that, if real GRS 1227 + 025 must represent a transient event or be very highly obscured (N-H greater than or equal to 10(24) cm(-2)).