Halo orbits of the earth (Farquhar, 1970) and their stationkeeping control are investigated analytically in the framework of the restricted three-body problem, and numerical algorithms based on the results are demonstrated, summarizing the report of Gomez et al. (1985). The semianalytical approach employed is explained; the halo-orbit neighborhood

The IRAS observations of well-known Seyfert galaxies have been studied in comparison with previously published ultraviolet and mid-infrared data. The mid- and far-infrared emission from Seyfert galaxies has an important extended component. Moreover, the UV-optical continuum is insufficient to account for the far-infrared emission via dust

IAUC 4261 available at Central Bureau for Astronomical Telegrams.

PG 1351+64 is a bright radio quiet quasar (z = 0.088, mV ≅ 14). IUE observations obtained within few months in 1982 - 1983 showed variations in the 1200 - 2000 Å band up to a factor of 2. Since then the object has been monitored regularly. The observations of 1984 - 1986, including also archival data, have more than doubled the number of available

Not Available

IAUC 4257 available at Central Bureau for Astronomical Telegrams. IAUC 4257 available at Central Bureau for Astronomical Telegrams.