SIMBAD references

A full-sky Hα map with 6' (FWHM) resolution is presented. This map is a composite of the Virginia Tech Spectral line Survey (VTSS) in the north and the Southern H-Alpha Sky Survey Atlas (SHASSA) in the south. The Wisconsin H-Alpha Mapper (WHAM) survey provides a stable zero point over 3/4 of the sky on a 1° scale. This composite map can be used to provide limits on thermal bremsstrahlung (free-free emission) from ionized gas known to contaminate microwave-background data. The map is available on the World Wide Web for public use.