The stellar content of the Orion OB1 association

We present a photometric investigation, using the VBLUW system, of the stellar content of Orion OB1. Physical parameters (logg, logT _eff) for the stars are derived with the aid of model atmospheres. From these, visual extinctions, absolute magnitudes and distance moduli are derived. The distance moduli are used to determine membership for the stars in each of the subgroups and distances to the subgroups are calculated. The ages of the subgroups are derived through isochrone fitting and the IMF is derived for each subgroup. The energy deposited into the ISM through stellar winds and supernovae is calculated and compared to observed large scale features in the ISM around Orion OB1.     

MultiWaveLink: An interactive data base for the coordination of multiwavelength and multifacility observations

MultiWaveLink is an interactive, computerized data base that was developed to facilitate a multiwavelength approach to studying astrophysical sources. It can be used to access information about multiwavelength resources (observers, telescopes, data bases and analysis facilities) or to organize observing campaigns that require either many telescopes operating in different spectral regimes or a network of similar telescopes circumspanning the Earth.     

The structural features of the germanium-silicon solid solution crystals obtained under microgravity

Structural features of germanium-silicon solid solution crystals have been investigated and silicon distribution in the crystals has been studied. All the crystals obtained under microgravity had, in spite of good external shape and facetting, a poorer internal structure than those obtained on Earth. The distribution of silicon have been shown to be non-uniform. High dislocation densities were observed.     

The sensitivity of the earth's radiation budget to changes in cloudiness

Cloudiness modulates the radiation budget at the top of the Earth-atmosphere system. For radiation balance studies, for climate diagnostic studies, and for climate modeling studies, it is important to know the sensitivity of both the outgoing longwave radiation and the net (absorbed solar minus outgoing longwave) radiation of the system to changes in cloudiness on a global basis. Based on a 45 month series of NOAA satellite scanning radiometer observations, estimates of the global distribution of these sensitivity parameters are obtained.     

Lightweight (AlGaAs)GaAs/CuInSe2 tandem junction solarcells for space applications

Mechanically stacked tandem cells consisting of GaAs thin-film upper cells and CuInSe₂ thin-film lower cells have been developed to meet the increasing power needs projected for future spacecraft. The authors report the fabrication of the first highly efficient lightweight GaAs/CuInSe₂ tandem cell on a 2-mil thick substrate, update recent performance improvements in thin-film GaAs/CuInSe₂ tandem cells, and discuss their application to space power systems. The efficiency of 4-cm² cells has improved to 21.6% AM0, the highest ever reported for a thin-film photovoltaic cell. Lightweight 4-cm² tandem cells have been successfully fabricated with efficiencies as high as 20.8%. These cells weighed about 180 mg without optimized substrate trimming. Radiation and operating temperature effects on GaAs/CuInSe₂ tandem cells are also discussed, and an interconnect scheme to form a voltage-matched string is described     

Sensor compensation for vehicle magnetic signatures

Most land vehicles whose positions need to be tracked are made primary of steel. The problem considered is that of finding locations within or on land vehicles where magnetic sensors can be mounted to measure heading accurately and of finding compensation methods that minimize the effect of the vehicle magnetic signature. Results obtained with various types of vehicles in several world locations are given. Advantages and disadvantages of pendulous mounting are considered, and vehicle magnetic changes caused by driving in areas of extremely strong magnetic fields such as those generated by DC-powered trains are discussed     

Electrical power distribution on space based radar satellites

The radar payload on a space-based radar (SBR) satellite could require tens of kilowatts of power distributed to many small loads over a large area. This poses special problems for the power distribution and control system (PDCS). A study that examined the power requirements of an SBR spacecraft is reported. A baseline prime power system, generating about 30 kW, was derived. The proposed distribution network would transmit 240 V at 20 kHz. The voltage would be downconverted in one converter for about 100 transmit/receive modules. The design considerations are discussed, and the baseline PDCS is described     

Physical interpretation of interdisciplinary solar/interplanetary observations relevant to the 27–29 June 1980 SMY/STIP event no. 5

A sequence of six well defined interplanetary structures (magnetic clouds) was identified in the solar wind and magnetic field measurements of Helios-1 from 29 June-01 July, 1980. (location 0.64–0.67 AU, C. Long. ～165°, C. Lat. ～5.8°). These structures were characterized by a large northward directed solar wind flow; by well defined directional discontinuities of mainly the ‘tangential-type’ at their beginnings and ends; by some increase in proton and by very pronounced increases in alpha particle number densities - each accompanied by sudden temperature decreases (or in one case by an increase); by some times an increase in magnetic field strength and by values of Nα/Np typical of the inner solar atmosphere. These structures are suggested to have been ejections from a succession (27–29 June, 1980) of Type II producing flares in Hale Region 16923 which coronagraph and X-ray (GOES) data indicate constituted a family of transient producing events. Only two interplanetary shocks were identified in the relevant Helios-1 records. It is suggested on the basis of observations of the directionality of certain of the flare related Type II bursts that some of these shocks could have been missed by the spacecraft. This implies that, in the absence of directional information, correlation of an observed interplanetary shock wave with a solar Type II burst may not always lead to a unique result.