We examine the status of the threat posed to stellar-mass black hole candidates by the possible existence of Q-stars (compact objects with an exotic equation of...

Swift J1756.9-2508 was discovered by the X-ray satellite Swift during an outburst in 2007 (ATEL #1105) and recognized immediately as an accretion-driven...

We present simultaneous high time resolution (1-10 Hz) X-ray and optical observations of the persistent LMXBs Sco X-1 and V801 Ara( = 4U 1636-536). In the case...

The accreting millisecond X-ray pulsar SAX J1808.4-3658 recently exhibited another outburst in September and October 2008 (ATel #1728). During this outburst, on...

Following the refined position of the faint X-ray transient XTE J1728-295 (ATel #2824) also named IGR J17285-2922 and currently in outburst (ATel #2823, #2825)...

We report the discovery of a previously unseen X-ray source detected in a 5ks Chandra/ACIS observation starting on 2008-11-27.72 UT as part of our ongoing...

We report the discovery of a previously unseen X-ray source detected in a 5ks Chandra/ACIS observation starting on 2009-03-11.59 UT as part of our ongoing...

Based on a 5ks Chandra ACIS-I observation of M31 on Nov 11 2009, we report a dramatic brightening of CXOM31 J004321.1+411751, [aka r3-7 (Kong et al. 2002 ApJ...

We report the discovery of 2 previously unseen X-ray sources detected in a 5ks Chandra/ACIS observation starting on 2008-09-01.32 UT as part of our ongoing...