NGC 592.-This is an H II region in M33, but unlike NGC 588, the combined
O-star spectrum does not provide a simple continuum, and this sight line
is not included in the final sample.
RH 4 (M33 X-3).-This source is located within the giant H II region
NGC 592 (V86-22; HS 59, Humphreys & Sandage 1980). ROSAT PSPC, radio
continuum, and optical spectroscopy observations have determined that
there is a supernova remnant (SNR 013022+30233) embedded in the H II
region (Gordon et al. 1993). The SNR is 5.4" +/- 4" away from RH 4 and
has an optical radius of 3"4.