1973 · 10 citations · 0 references
The number of young open star clusters previously studied with three- color photometry (Becker and Fenkart, 1971: 88) now stands at 110. Revisions for four clusters are given, of which Pismis 20 is especially interesting. This cluster coincides with the supernova remnant G 320.4 -- 1.2 and the x-ray source 2 U 1509-- 58. The distribution of young clusters is compared with that of five other young spiral tracers out to -4 kpc from the Sun. The most interesting features are: a filament protruding from the local arm at 1 = 270 deg and an abrupt discon tinuation of the local arm beyond 1.6 kpc at 1 = 235 deg . (auth)