Absolute Hα and Hβ Photometry of LMC HII Regions

A nebular photometer equipped with a scanning Fabry-Perot interferometer has been used at the ESO 50-cm telescope to observe about 50 HII regions of the LMC (Caplan and Deharveng, 1983). This instrumentation gives the profiles of the observed lines, thus allowing discrimination against unwanted continuum and line emission. The integrated fluxes were measured with a 4.9′ diaphragm, to facilitate comparison with the 6-cm radio continuum fluxes obtained by McGee et al. (1972) with a similar resolution. Nebular reddening, from the Hα/Hβ ratio, is greatest for the 30 Doradus Nebula. Relatively high reddening was also observed for the following zones: N159 (at the border of the largest HI-molecular complex of the LMC) and N160; N79, N81 and N83; N48; N64. Reddening is rather low towards other HII regions, especially for those in the bar and for large bubble-shaped regions.