A Preliminary Analysis of a New Chandra Observation (ObsID 6148) of Cir X-1

We present the preliminary spectral analysis of a 25 ks long Chandra observation of the peculiar source Cir X-1 near the periastron passage. We estimate more precise coordinates of the source compatible with the optical and radio counterpart coordinates. We detect emission lines associated to Mg XII, Si XIII, Si XIV, S XV, S XVI Ar XVII, Ar XVIII, Ca XIX, Ca XX, Fe XXV, Fe XXVI showing a redshift of 470 km s-1. The more intense emission features at 6.6 keV show a double-peaked shape that can be modelled with two or three Gaussian lines