  Recent Swift X-ray monitoring campaigns of novae have revealed extreme levels
of variability during the early super-soft-source (SSS) phase. The first time
this was observed was during the 2006 outburst of the recurrent nova RS Oph
which was also extensively covered by grating observations with XMM-Newton and
Chandra. I focus here on an XMM-Newton observation taken on day 26.1, just
before Swift confirmed the start of the SSS phase, and a Chandra observation
taken on day 39.7. The first observation probes the evolution of the shock
emission produced by the collision of the nova ejecta with the stellar wind of
the companion. The second observation contains bright SSS emission longwards of
15A while at short wavelengths, the shock component can be seen to have hardly
changed. On top of the SSS continuum, additional emission lines are clearly
seen, and I show that they are much stronger than those seen on day 26.1,
indicating line pumping caused by the SSS emission. The lightcurve on day 39.7
is highly variable on short time scales while the long-term Swift light curve
was still variable. In 2007, we have shown that brightness variations are
followed by hardness variations, lagging behind 1000 seconds. I show now that
the hardness variations are owed to variations in the depth of the neutral
hydrogen column density of order 25%, particularly affecting the oxygen K-shell
ionization edge at 0.5 keV.
