The X-ray and optical variability of the BLRG 3C390.3

We describe the optical emission line and continuum changes in 3C390.3. Also we present new EXOSAT results, and discuss their implication for determination of the X-ray spectrum — spectral index and absorbing column.     

History of Time-Frequency Technology

Present-day collision avoidance systems (CAS) of the time-frequency variety employ modes of operation similar to those of airborne equipment which has been operating in military aircraft since 1959. A fleet operational evaluation of these systems began in 1961 in aircraft of U. S. Navy Helicopter Squadron HS-4, based on the aircraft carrier U.S.S. Yorktown. This equipment utilized a local clock in each aircraft, a separate time slot for each aircraft's interrogation signal, air-to-air coarse synchronization of all stations, and sufficient free-drift stability for time slot keeping. Operational use of one-way ranging with elimination of propagation delay offsets, higher clock stability for open-loop time keeping in the SNS-64 ... AN/APN-169 family of systems began in 1964 in U. S. Air Force C-130E turboprop aircraft. In 1965, use of the EROS I collision avoidance system began during flight testing of F-4 Phantom supersonic aircraft.     

Editorial: Cognitive Semantics and Spatio-Temporal Ontologies

How do people describe the location of a target object to another? This task requires a reference object or frame and terms of reference. Traditional linguistic analyses have loosely organized perspectives around people, objects, or environments as reference objects, using reference terms based on a viewpoint or the intrinsic sides of an object, such as left, right, front, and back or based on the environment, such as north, south, east, and west. In actual communication, social, spatial, and cognitive factors may also affect perspective choice. We examine those factors by varying the spatial information (landmarks and cardinal directions), the communication task (relative cognitive burden to speakers and addressees), and the culture of participants (American and Japanese). Speakers used addressees' perspectives more when addressees had the greater cognitive burden. They also used landmarks and cardinal directions when they were available, especially to avoid difficult discriminations like left/right. Some cases appearing to be perspective taking can be interpreted as using a person as a landmark. Finally, terms like near indicating close proximity were preferred to far and to terms requiring projection of directions. Globally, perspective choices of American and Japanese samples were strikingly similar; that is, Japanese did not select addressees' perspectives more than Americans. The traditional linguistic analyses need to be enhanced to account for effects of cognitive, situational, and social factors.     

FEM code simulation of the magnetospheric proton fluxes

We report a study of the numeric solution to the diffusive transport equation for energetic protons magnetically trapped in the Earth's equatorial magnetosphere. The analysis takes into account the pertinent physical processes in this region, including deceleration of protons by Coulomb collisional interactions with free and bound electrons, the charge exchange process, cosmic ray albedo neutron decay source, and electric and magnetic radial diffusion. These results were obtained using the Finite Element Method with magnetic moment and geomagnetic L-shell as free variables. Steady state boundary conditions were imposed at L=1 as zero distribution function and at L=7 with proton distribution function extracted from ATS 6 satellite observations. The FEM-code yields unidirectional proton flux in the energy range of 0.1–1000 MeV at the equatorial top of the geomagnetic lines, and the results are found to be in satisfactorily agreement with the empirical NASA AP-8 model proton flux within the energy range of 0.5–100 MeV. Below 500 keV, the empirical AP-8 model proton fluxes are several orders of magnitude greater than those computed with the FEM-code at L<3. This discrepancy is difficult to explain by uncertainties of boundary spectrum parameters or transport coefficients.     

On small active region filaments,fibrils and surges

High resolution Hα images and magnetograms (0.2 arc s) of an active region were obtained in alternating time series at 42 s cadences using the Swedish 1-m Solar Telescope on 2004 August 21. The Hα filtergrams reveal an active region filament and surges consisting of thread-like structures which have widths similar to the widths of chromospheric fibrils, both recorded down to the resolution limit in the best images. All observed structures in the active region appear highly dynamic. Fibrils show counterstreaming strongly resembling the counterstreaming threads in filaments.     

Comet nucleus sample return: Plans and capabilities

ROSETTA — the Comet Nucleus Sample Return mission — is one of the four Cornerstone missions to which ESA has committed itself in its approved Long-Term Programme Horizon 2000. The mission is currently being studied in collaboration with NASA. The comet-nucleus samples that ROSETTA is to provide will allow us to study some of the most primitive material in the solar system and the physical and chemical processes that marked the beginning of the system 4.6 billion years ago. For ESA, ROSETTA is a new type of mission: one which will return a sample at cryogenic temperature, and where as much effort has to be spent on preparing the laboratory analysis on-ground as has to be invested in preparing the space segment with the sample acquisition and in situ documentation. As part of the preparation for this mission, ESA is now starting to consider Planetary Protection issues.     

The cosmic ray solar diurnal anisotropy

This paper reviews the present state of knowledge concerning the diurnal and semidiurnal variations in the galactic cosmic ray intensity. The analytical procedures that are required for extracting from the original data the desired information concerning the characteristics of the anisotropies outside the magnetosphere are described. These include corrections for atmospheric fluctuations, the determination of the amplitudes and phases of the daily variations, and their interpretation in terms of the free space anisotropies that give rise to them. The experimental results concerning the 24-h wave, including its long-term variations with periods of one and two solar cycles, and the characteristics of the total diurnal anisotropy are then discussed. The semidiurnal anisotropy is considered next. Transient anisotropies which manifest themselves as day-to-day variations, recurrence tendencies, cosmic ray storms, and diurnal variation trains, and which can introduce appreciable changes in the spectral parameters, are also of interest. The evolution of theoretical models developed to account for the diurnal and semidiurnal anisotropies, and fluctuations thereof, are then discussed in the light of the experimental results. Finally, the general features that are now well established, and the nature of the remaining problems, are summarized.