  The X-ray transient, 4U 1730-22, has not been detected in outburst since
1972, when a single outburst was detected by the Uhuru satellite. This neutron
star or black hole X-ray binary is presumably in quiescence now, and here, we
report on X-ray and optical observations of the 4U 1730-22 field designed to
identify the system's quiescent counterpart. Using Chandra, we have found a
very likely counterpart. The candidate counterpart is close to the center of
the Uhuru error region and has a thermal spectrum. The 0.3-8 keV spectrum is
well-described by a neutron star atmosphere model with an effective temperature
of 131+/-21 eV. For a neutron star with a 10 km radius, the implied source
distance is 10(+12)(-4) kpc, and the X-ray luminosity is 1.9E33 ergs/s assuming
a distance of 10 kpc. Accretion from a companion star is likely required to
maintain the temperature of this neutron star, which would imply that it is an
X-ray binary and therefore, almost certainly the 4U 1730-22 counterpart. We do
not detect an optical source at the position of the Chandra source down to R >
22.1, and this is consistent with the system being a Low-Mass X-ray Binary at a
distance greater than a few kpc. If our identification is correct, 4U 1730-22
is one of the 5 most luminous of the 20 neutron star transients that have
quiescent X-ray luminosity measurements.
