  Eclipse lightcurves of the dwarf nova IP Peg during the November 1996
outburst are analysed with eclipse mapping techniques to constrain the location
and investigate the spatial structure of the spiral shocks observed in the
Doppler tomograms (Harlaftis et al. 1999). Eclipse maps in the blue continuum
and in the CIII+NIII 4650 emission line show two asymmetric arcs of \sim 90
degrees in azimuth and extending from intermediate to the outer disc regions (R
\simeq 0.2 - 0.6 R_{L1}, where R_{L1} is the distance from disc centre to the
inner Lagrangian point) which are interpreted as being the spiral shocks seen
in the Doppler tomograms. The HeII 4686 eclipse map also shows two asymmetric
arcs diluted by a central brightness source. The central source probably
corresponds to the low-velocity component seen in the Doppler tomogram and is
understood in terms of gas outflow in a wind emanating from the inner parts of
the disc. We estimate that the spirals contribute about 16 and 30 per cent of
the total line flux, respectively, for the HeII and CIII+NIII lines. Comparison
between the Doppler and eclipse maps reveal that the Keplerian velocities
derived from the radial position of the shocks are systematically larger than
those inferred from the Doppler tomography indicating that the gas in the
spiral shocks has sub-Keplerian velocities. We undertake simulations with the
aim to investigate the effect of artifacts on the image reconstruction of the
spiral structures.
