Chandra Observations of the Bursting X-Ray Transient SAX J1747.0-2853 during Low-Level Accretion Activity

We present Chandra/ACIS observations of the bursting X-ray transient SAX J1747.0-2853 performed on 2001 July 18. We detected a bright source at the position of R. A. = 17(h)47(m)02.(s)60 and decl. = -28degrees52'58."9 (J2000.0, with a 1 sigma error of similar to0."7), consistent with the BeppoSAX and ASCA positions of SAX J1747.0-2853 and with the Ariel V position of the transient GX + 0.2-0.2, which was active during the 1970s. The 0.5-10 keV luminosity of the source during our observations was similar to3 x 10(35) ergs s(-1) ( assuming a distance of 9 kpc), demonstrating that the source was in a low-level accretion state. We also report on the long-term light curve of the source as observed with the all-sky monitor on board the Rossi X-Ray Timing Explorer. After the initial 1998 outburst, two more outbursts ( in 2000 and 2001) were detected with peak luminosities about 2 orders of magnitude larger than our Chandra luminosity. Our Chandra observation falls between those two outbursts, making the outburst history for SAX J1747.0-2853 complex. Those bright 2000 and 2001 outbursts, combined with the likely extended period of low-level activity between those outbursts, strongly suggest that the classification of SAX J1747.0-2853 as a faint X-ray transient was premature. It might be possible that the other faint X-ray transients can also exhibit bright, extended outbursts that would eliminate the need for a separate subclass of X-ray transients. We discuss our results also in the context of the behavior of X-ray binaries accreting at low levels with luminosities around 10(35) ergs s(-1), a poorly studied accretion rate regime.