Measuring Black Hole Spins: ToO Observations of a Black Hole Transient

We propose two 20 ksec long Target of Opportunity observations of a bright blackhole transient in outburst, to study the relativistic Fe Kα line profileand its variability in such systems, and to perform Xray timing studies. Felines probe the innermost regions of accretion disks where the gravitationalfield is the most intense. To obtain a maximum signal to noise ratio in theline, these observations will be using the modified timing mode of the EPICpncameras, recently employed successfully in observations of the relativistic lineof Cygnus X1. The accurate measurement of the line shape will then lead toconstraints on the black hole spin. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]