De-occultation x-ray events of 2 December, 1967

A flare rising from behind the solar limb was recorded simultaneously by the UCSD X-ray detector on OSO-III (7.7–200 keV) and the Caltech photoheliograph on Robinson Laboratory roof (Hα). The de-occultation gives excellent spatial resolution of the X-ray source. Spectra suggest that the material was already heated to 27 000 000° and that the increase in flux was due to the de-occultation. The flux rise to maximum was proportional to the apparent area. The uniformity of this rise shows that there was no special kernel of emission. Comparison of the deduced volume with the bremsstrahlung formula gives a density of about 10¹⁰ for the 27 000 000° component of the flare; this is confirmed by consideration of the maximum possible coulomb braking. The actual decay is more likely by escape rather than coulomb braking.     

Distribution and composition of phytoplankton in northeastern coastal waters of the United States

Results are given from collections made during eight cruises over the northeastern continental shelf. Seasonal phytoplankton assemblages are noted, which include a variety of ultraplankton components. Areas of greatest cell concentrations were at near shore stations, Georges Bank, and at scattered sites over the shelf. Dominant species included Skeletonema costatum, Asterionella glacialis and Leptocylindrus danicus.