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In this letter we communicate the identification of a new Galactic O2If* star(MTT 68) isolated at a projected linear distance of 3 pc from the centre of thestar-burst cluster NGC 3603. From its optical photometry I computed abolometric luminosity M_Bol = -10.7, which corresponds to a total stellarluminosity of 1.5 x 10^{6} L_Sun. It was found an interesting similaritybetween MTT 68 and the well known multiple system HD 93129. From Hubble SpaceTelescope F656N images of the NGC 3603 field, it was found that MTT 68 isactually a visual binary system with an angular separation of 0.38 arcsec,which corresponds to a projected (minimum) linear distance of r_(A-B) = 1.4 x10^{-2} pc. This value is similar to that for the HD 93129A (O2If*) and HD93129B (O3.5) pair, r_(A-B) = 3.0 x 10^{-2} pc. On the other hand, HD93129A hasa third closer companion named HD 93129Ab (O3.5) at only 0.053 arcsec, andtaking into account that the X-ray to total stellar luminosity ratio for theMTT 68 system (L_X/L_Bol 10^{-5}) is about two orders of magnitude above thecanonical value expected for single stars, I suspect that the MTT 68 systemprobably hosts another massive companion not resolved by the HST archiveimages.

An O2If* star found in isolation in the backyard of NGC 3603