INTERSTELLAR REDDENING FOR PLANETARY-NEBULAE TOWARD GALACTIC BULGE

Spectrophotometric data for six planetary nebulae in the direction of the galactic bulge were used to derive the properties of the interstel lar reddening for this region. The observed nebular continuum was comp ared with theoretically predicted nebular continuum and the interstell ar reddening was evaluated from she differences. The derived reddening function for each nebula shows generally good agreement with the Whit ford reddening law in long wavelengths of visible region. However, the re exist significant deviations from the standard law in ultraviolet, which may be explained by either different composition or different si ze distribution of the dust grains lying toward the galactic center. A rough estimate suggests R = 1.5 similar to 2.0, which is significantl y smaller than the standard value of R = 3.