Interstellar Extinction Law in the Vicinity of the North America and Pelican Nebulae The interstellar reddening law is derived for 15 heavily reddened starsin the area which includes the North America and Pelican nebulae and thedark cloud between them. The method is based on photometry of thesestars in the Vilnius seven-color system and on their MK spectral types.The mean law in this area is very similar to the law for a much widerarea in Cygnus derived earlier by other authors. It differs from thenormal law by exhibiting somewhat stronger extinction in the violet andthe near ultraviolet spectral region, i.e., it shows a smaller ``knee"in the blue part of the spectrum.
UBV beta Database for Case-Hamburg Northern and Southern Luminous Stars A database of photoelectric UBV beta photometry for stars listed in theCase-Hamburg northern and southern Milky Way luminous stars surveys hasbeen compiled from the original research literature. Consisting of over16,000 observations of some 7300 stars from over 500 sources, thisdatabase constitutes the most complete compilation of such photometryavailable for intrinsically luminous stars around the Galactic plane.Over 5000 stars listed in the Case-Hamburg surveys still lackfundamental photometric data.
The interstellar 217 NM band - A third catalogue of equivalent widths A catalog of equivalent widths of the 217 nm interstellar absorptionband as well as other parameters characterizing the extinction curve inthe ultraviolet has been compiled for 790 O and B stars. A relativelytight correlation between the equivalent width of the 217 nm band andE(B-V) indicates that the absorber of this band is connected with thepopulation of larger interstellar grains responsible for the visualextinction. The parameter characterizing the amount of extinction in thefar UV is only weakly correlated with E(B-V), a result in accord withthe assumption that a second population of very small grains causes therapid increase of the far-UV extinction.
A catalog of ultraviolet interstellar extinction excesses for 1415 stars Ultraviolet interstellar extinction excesses are presented for 1415stars with spectral types B7 and earlier. The excesses with respect to Vare derived from Astronomical Netherlands Satellite (ANS) 5-channel UVphotometry at central wavelengths of approximately 1550, 1800, 2500, and3300 A. A measure of the excess extinction in the 2200-A extinction bumpis also given. The data are valuable for investigating the systematicsof peculiar interstellar extinction and for studying the character of UVinterstellar extinction in the general direction of stars for which theextinction-curve shape is unknown.
