4 Summary

The OH and H$_{\rm 2}$O masers observed at the VLA by FC89 represent a large sample of massive star-forming regions containing both maser species in the galaxy. The masers are often associated with ultra-compact HII regions, dense molecular cores, FIR objects and molecular outflows. The relationship between the masers and these other objects, and with the massive stars which are the presumed energy source for the masers, remains an active area of research. Until this relationship is better understood, the promise of these bright molecular-line sources to probe the environment of massive star-forming complexes will not be fulfilled.

We have provided in electronic form the complete VLA database of interstellar OH and H$_{\rm 2}$O masers analyzed by FC89. Maps, spectra and beams are shown for all 74 fields observed. Several changes to the original database, and some caveats to its use for spatial and kinematical analysis were discussed. The database will be useful in interpreting continuum and molecular line observations of star-forming regions, for investigating the spatial and kinematical relation between the masers and their local environment, and in studies of the spatial and temporal evolution of the OH and H$_{\rm 2}$O masers themselves.