The X-ray source SLX 1732-304 in the globular cluster Terzan 1: The spectral states and an X-ray burst

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Abstract
ART-P/Granat observations of the X-ray burster SLX 1732-304 in the globular cluster Terzan 1 are presented. The X-ray (3–20 keV) fluxes from the source differed by more than a factor of 4 during the observing sessions on September 8 (Fx ≃ 6.95 × 10−10 erg cm−2 s−1) and October 6, 1990 (Fx ≃ 1.64 × 10−10 erg cm−2 s−1). The intensity variations of SLX 1732-304 were apparently accompanied by variations in its hardness: whereas the source in its high state had the spectrum with a distinct exponential cutoff typical of bright low-mass X-ray binaries, its low-state spectrum could be satisfactorily described by a simple power law with a photon index α≃1.7. During the ART-P observation on September 8, a type I X-ray burst was detected from SLX 1732-304.