LARGE-SCALE [CII] LINE EMISSION IN THE GALAXY OBSERVED BY STRATOSPHERIC BALLOONS

By using a balloon borne telescope, an extensive survey of the [CII] l ine emission of the Galaxy has been undertaken. To minimize the instru mental emission, an off-axis telescope with a Newtonian-Nasmyth focus was used in conjunction with a liquid helium cooled Fabry-Perot spectr ometer. The beam size of the telescope was 12' in diameter and the spe ctral resolution of the spectrometer was 175 km/s in velocity scale. T he balloon flights were made from Palestine, TX in 1991 and from Alice Springs, Australia in 1992. By both observations, the major part of t he galactic plane in the northern sky and the southern sky has been sc anned. As a result, a complete map of the [CII] line intensity distrib ution has been constructed for the region from -100-degrees to 80-degr ees in galactic longitude and within +/-4-degrees in galactic latitude . In addition to the general scan of the galactic plane, the observati ons were extended to some individual sources, such as Cyg-X region, rh o-Oph dark cloud and Large Magellanic Cloud. The observed maps reveal strong [CII] line emission extensively distributed in the galactic pla ne, as well as many discrete sources associated with HII regions and/o r molecular clouds. The distribution is more or less correlated with f ar infrared continuum and CO line intensity distributions. However, de tailed comparisons show interesting differences between the three comp onents.