Introduction

While we can study some H II regions, supernova remnants (SNRs), planetary nebulae (PNe), and other nebular structures in detail in our own Galaxy, we lack the global perspective to study their general properties, especially in the optical where interstellar absorption prevents observations of all but the relatively local environment. Studies of distant galaxies provide the global view, but are limited in their ability to examine the detailed interactions on the scales of filaments or stars. The Large and Small Magellanic Clouds are unique in providing us with sites to study the interstellar medium (ISM) and its components at all scales. Their proximity and low foreground absorption make them the ideal laboratories for both studies of individual H II regions, SNRs, and superbubbles, and investigations of the global properties using samples of these objects.

To undertake such research, uniform datasets are needed to provide the basis for the identification, classification, and detailed study of the many components of the ISM. Until recently, optical surveys of the ISM in the Magellanic Clouds were limited to photographic studies performed in individual emission lines (e.g. H in Davies, Elliot, & Meaburn 1976, [O III] in Morgan et al. 1995). More recent surveys with modern CCD detectors have generally been limited either in area or in resolution (e.g. Kennicutt et al. 1995). With the relatively recent combination of a large format CCD detector with the Schmidt telescope at CTIO, we have undertaken a deep multiple emission-line CCD survey of both the LMC and SMC, known as the UM/CTIO Magellanic Cloud Emission-line Survey (MCELS).

© Copyright Astronomical Society of Australia 1997