First XMM-Newton observations of an isolated neutron star: RX J0720.4-3125 F. Paerels, K. Mori, C. Motch, F. Haberl, V. E. Zavlin, S. Zane, G. Ramsay, M. Cropper and B. Brinkman A&A, 365 1 (2001) L298-L301 Published online: 15 January 2001 DOI: 10.1051/0004-6361:20000059