2003ApJ...598..474M

We report Chandra and XMM-Newton observations of the transient neutron star low-mass X-ray binary GRS 1741.9-2853. Chandra detected the source in outburst on 2000 October 26 at an X-ray luminosity of ∼10³⁶ ergs/s (2-8 keV; 8 kpc), and in quiescence on 2001 July 18 at ∼10³² ergs/s. The latter observation is the first detection of GRS 1741.9-2853 in quiescence. We obtain an accurate position for the source of 17^h45^m2{fs}33, -28°54'49".7 (J2000), with an uncertainty of 0".7. GRS 1741.9-2853 was not detected significantly in three other Chandra observations, nor in three XMM-Newton observations, indicating that the luminosity of the source in quiescence varies by at least a factor of 5 from (<0.9-5.0)x10³² ergs/s (2-8 keV). A weak X-ray burst with a peak luminosity of 5x10³⁶ ergs/s above the persistent level was observed with Chandra during the outburst on 2000 October 26. The energy of this burst, 10³⁸ ergs, is unexpectedly low and may suggest that the accreted material is confined to the polar caps of the neutron star. A search of the literature reveals that GRS 1741.9-2853 was observed in outburst with ASCA in the fall of 1996 as well, when the BeppoSAX WFC detected the three previous X-ray bursts from this source. The lack of X-ray bursts from GRS 1741.9-2853 at other epochs suggests that it produces bursts only during transient outbursts when the accretion rate onto the surface of the neutron star is about 10^–10 M_☉yr^–1. A similar situation may hold for other low-luminosity bursters recently identified from WFC data.