In ATel #1815 we erroneously associated the globular cluster M31GC J004234+405709 (Bol 117) with object s1-1 from Williams et al. (2006, ApJ 643, 356). Bol 117...

Observations of the optical counterpart to XTE J1650-500 with the Magellan 1 telescope find it fainter than expected based on reports of it's possible detection...

We discuss the method, and potential systematic effects therein, used for measuring the mass of stellar-mass black holes in X-ray binaries. We restrict our...

We find that the mass ratio q in quiescent black hole (BH) X-ray transients is tightly correlated with the ratio of the double-peak separation (DP) to the full...

On 2015 June 15, the Swift space observatory discovered that the Galactic black hole candidate V404 Cyg was undergoing another active X-ray phase, after 25...

We report on a pointed RXTE/PCA observation of the transient source MAXI J1659-152 (Atel #2873,#2874,#2875,#2877,#2880 GCN #11296,#11299, #11307 - initially...

Since its discovery in 1992, the superluminal X-ray transient GRS 1915+105 has been extensively observed in an attempt to understand its behaviour. We present...

We present high time-resolution multicolour observations of the quiescent soft X-ray transients V404 Cyg and XTE J1118+480 obtained with ULTRACAM. The power...