  V4743 Sgr (Nova Sgr 2002 No. 3) was discovered on 20 September 2002. We
obtained a 5ks ACIS-S spectrum in November 2002 and found that the nova was
faint in X-rays. We then obtained a 25ks CHANDRA LETGS observation on 19 March
2003. By this time, it had evolved into the Super Soft X-ray phase exhibiting a
continuous spectrum with deep absorption features. The light curve from the
observation showed large amplitude oscillations with a period of 1325s (22min)
followed by a decline in total count rate after ~13ks of observations. The
count rate dropped from ~40cts/s to practically zero within ~6ks and stayed low
for the rest of the observation (~6ks). The spectral hardness ratio changed
from maxima to minima in correlation with the oscillations, and then became
significantly softer during the decay. Strong H-like and He-like lines of
oxygen, nitrogen, and carbon were found in absorption during the bright phase,
indicating temperatures between 1-2MK, but they were shifted in wavelength
corresponding to a Doppler velocity of -2400km/s. The spectrum obtained after
the decline in count rate showed emission lines of CVI, NVI, and NVII
suggesting that we were seeing expanding gas ejected during the outburst,
probably originating from CNO-cycled material. An XMM-Newton ToO observation,
obtained on 4 April 2003 and a later LETGS observation from 18 July 2003 also
showed oscillations, but with smaller amplitudes.
