• Peter Jonker (Co-leader; SRON, University of Nijmegen & CfA) • Rudy Wijnands (Co-leader; University of Amsterdam) • David Bersier (Liverpool John Moores University) • Catherine Brocksopp (Mullard Space Science Laboratory) • Stephane Corbel (University Paris Diderot & CEA Saclay) • Ed Daw (University of Sheffield) • Vik Dhillon (University of Sheffield) • Alexander van der Horst (University of Amsterdam) • Lucien Kuiper (SRON) • Casey Law (University of California, Berkeley) • Sera Markoff (University of Amsterdam) • James Miller-Jones (Curtin Institute of Radio Astronomy) • Teo Muñoz-Darias (University of Southampton) • Paul O'Brien (University of Leicester) • Anthony Rushton (ESO & Onsala Space Observatory) • Adam Stewart (University of Southampton) • Valeriu Tudose (ASTRON) • Anna Watts (University of Amsterdam) • Patrick Woudt (University of Cape Town) Importance of counterparts at other wavebands shown in Frail et al. 2011