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We have applied a new reconstruction method (Sonnerup andTeh, 2008), based on the ideal single-fluid MHD equations in a steady-state,two-dimensional geometry, to a reconnection event observed by the Cluster-3(C3) spacecraft on 5 July 2001, 06:23 UT, at the dawn-sideNorthern-Hemisphere magnetopause. The event has been previously studied byuse of Grad-Shafranov (GS) reconstruction, performed in thedeHoffmann-Teller frame, and using the assumption that the flow effects wereeither negligible or the flow was aligned with the magnetic field. Our newmethod allows the reconstruction to be performed in the frame of referencemoving with the reconnection site (the X-line). In the event studied, thismotion is tailward/equatorward at 140 km/s. The principal result of thestudy is that the new method functions well, generating a magnetic field mapthat is qualitatively similar to those obtained in the earlier GS-basedreconstructions but now includes the reconnection site itself. In comparisonwith the earlier map by Hasegawa et al. (2004), our new map has a slightlyimproved ability (cc=0.979 versus cc=0.975) to predict the fields measuredby the other three Cluster spacecraft, at distances from C3 ranging from2132 km (C1) to 2646 km (C4). The new field map indicates the presence of amagnetic X-point, located some 5300 km tailward/equatorward of C3 at thetime of its traversal of the magnetopause. In the immediate vicinity of theX-point, the ideal-MHD assumption breaks down, i.e. resistive and/or othereffects should be included. We have circumvented this problem by an ad-hocprocedure in which we allow the axial part of convection electric field tobe non-constant near the reconnection site. The new reconstruction methodalso provides a map of the velocity field, in which the inflow into thewedge of reconnected field lines and the plasma jet within it can be seen,and maps of the electric potential and of the electric current distribution.Even though the velocity map is expected to be inaccurate near the X-point,it provides high-quality predictions (cc=0.969) of the velocity componentsat points along the path of C1, some of which are close to the X-point; thepredictions of density and pressure are less good. Except near thereconnection site, the new reconstruction provides a completecharacterization, in unprecedented detail, of the entire dynamic plasma andfield equilibrium, reconstructed from the C3 data. It represents our bestprediction to date of what the actual configuration was like. But, sincesubstantial time variations were present in the event, the recoveredstructure by necessity includes considerable time aliasing. The invariantdirection used in the reconstruction, is found to agree, within 6°,with a recent theoretical prediction of the X-line orientation by Swisdakand Drake (2007)

First results from ideal 2-D MHD reconstruction: magnetopause reconnection event seen by Cluster