Rei?, David G. Sibeck, George L. Siscoe, J. David Winningham, Joachim Woch, Masatoshi Yamauchi, Andrew W. Yau, and Qiugang Zong The editors of this special issue express deep gratitude to the Managing Editor of Surveys in Geophysics, Dr. Michael Rycroft, for his support during the project, which was "above and beyond the call of duty", and for his careful reading and his insightful comments on each of the papers published in this issue. Guest Editors THEODORE A. FRITZ Center for Space Physics Boston University Boston, MA 02215 USA SHING F. FUNG Space Physics Data Facility NASA Goddard Space Flight Center Greenbelt, MD 20771 USA Surveys in Geophysics (2005) 26: 5-55 DOI 10. 1007/s10712-005-1871-7 Springer 2005 CLUSTER OBSERVATIONS OF THE CUSP: MAGNETIC STRUCTURE AND DYNAMICS 1 2 3 4 M. W. DUNLOP , B. LAVRAUD , P. CARGILL , M. G. G. T. TAYLOR , 3 2 5 6 ' A. BALOGH ,H. REME , P. DECREAU , K. -H. GLASSMEIER , 4 2 7 2 R. C. ELPHIC , J. -M. BOSQUED , A. N. FAZAKERLEY , I. DANDOURAS , 8 8 9 C. P. ESCOUBET , H. LAAKSO and A. MARCHAUDON 1 SSTD, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, UK E-mail: m. dunlop@rl. ac.