  Hard X-ray imaging of the Galactic plane by the INTEGRAL satellite is
uncovering large numbers of 20-100 keV "IGR" sources. We present results from
Chandra, INTEGRAL, optical, and IR observations of 4 IGR sources: 3 sources in
the Norma region of the Galaxy (IGR J16195-4945, IGR J16207-5129, and IGR
J16167-4957) and one that is closer to the Galactic center (IGR J17195-4100).
In all 4 cases, one relatively bright Chandra source is seen in the INTEGRAL
error circle, and these are likely to be the soft X-ray counterparts of the IGR
sources. They have hard 0.3-10 keV spectra with power-law photon indices of 0.5
to 1.1. While many previously studied IGR sources show high column densities,
only IGR J16195-4945 has a column density that could be as high as 10^23 cm^-2.
Using optical and IR sky survey catalogs and our own photometry, we have
obtained identifications for all 4 sources. The J-band magnitudes are in the
range 14.9-10.4, and we have used the optical/IR spectral energy distributions
(SEDs) to constrain the nature of the sources. Blackbody components with
temperature lower limits of >9400 K for IGR J16195-4945 and >18,000 K for IGR
J16207-5129 indicate that these are very likely High-Mass X-ray Binaries
(HMXBs). However, for IGR J16167-4957 and IGR J17195-4100, low extinction and
the SEDs indicate later spectral types for the putative companions, indicating
that these are not HMXBs.
