  We report High Energy Transient Explorer 2 (HETE-2) Wide Field X-ray
Monitor/French Gamma Telescope observations of XRF030723 along with
observations of the XRF afterglow made using the 6.5m Magellan Clay telescope
and the Chandra X-ray Observatory. The observed peak energy E_pk_obs of the nu
F_nu burst spectrum is found to lie within (or below) the WXM 2-25 keV passband
at 98.5% confidence, and no counts are detected above 30 keV. Our best fit
value is E_pk_obs=8.4+3.5/-3.4 keV. The ratio of X-ray to Gamma-ray flux for
the burst follows a correlation found for GRBs observed with HETE-2, and the
duration of the burst is similar to that typical of long-duration GRBs. If we
require that the burst isotropic equivalent energy E_iso and E_pk_rest satisfy
the relation discovered by Amati et al. (2002), a redshift of z=0.38+0.36/-0.18
can be determined, in agreement with constraints determined from optical
observations. We are able to fit the X-ray afterglow spectrum and to measure
its temporal fade. Although the best-fit fade is shallower than the concurrent
fade in the optical, the spectral similarity between the two bands indicates
that the X-ray fade may actually trace the optical fade. If this is the case,
the late time rebrightening observed in the optical cannot be due to a
supernova bump. We interpret the prompt and afterglow X-ray emission as arising
from a jetted GRB observed off-axis and possibly viewed through a complex
circumburst medium due to a progenitor wind.
