[en] Wall shift limits the actual accuracy of the hydrogen maser to 10^-12. After a review of the perturbation of the hydrogen atoms upon collision on the surface of teflon coated bulb, a new approach is proposed in which a teflon cylinder replaces the classical storage bulb. In this case a more reproducible wall shift is expected. (author)

[en] An experimental verification of Einstein's equivalence principle has been made using an atomic hydrogen maser in a space probe attaining an altitude of 10,000 km above the earth's surface. At the present stage of the data reduction, confirmation is at the 2 x 10^-4 level of accuracy. The experiment and the resulting data are described including a comment on the limits to the anisotropy of the velocity of light. It is believed that this is the first direct, high-accuracy test of the symmetry of the propagation of light and a beginning in the use of high-accuracy clocks in space to measure relativistic phenomena. (author)

[en] In this work a synthesis method is applied to the design of an electron gun for a 94GHz gyrotron. Using the synthesis method, it is found the shape of the electrodes compatible with the laminar flow which minimizes the action of space change on the electron velocity dispersion. A sistematic procedure is presented to fuid the parameters of the synthesis method which, in turn, are closely related to the characteristics of the aptoclechonic system. (author)

[en] Positions of 65 OH maser sources obtained with the 100-m radio telescope are presented. The positional accuracy is typically 10'', a conservative estimate for sources stronger than approx.10 Jy. The emphasis of this work was on OH/IR sources and 51 of the objects are certain type II OH/IR sources, of which only one (GX Mon) is associated with an optically known star. Three of the sources show only one 1612-MHz line component and these are probably also OH/IR sources but with a large ratio between the intensities of the high- and low-velocity components. Six of the objects are certain type I OH sources, i.e., maser emission associated with recently formed massive stars, and five more are probably of this type, although in some of these cases the 1612-MHz line is stronger than one of the main lines. This work has incidentally revealed (i) that the 1665-MHz emission which previously was assumed to be positionally coincident with the 1720-MHz emission of the source ON-3 originates approx.2.'3 to the southwest of the interferometrically determined 1720-MHz position, and (ii) that to within the positional accuracy, the position of the 1612-MHz emission from the core of the Kleinmann--Low nebula (Orion) is the same as that of the 1665-MHz emission; (iii) that the position of the 1667-MHz emission from VX Sgr is the same as that of the 1612-MHz emission; and (iv) that the position of the 1612-MHz emission from W 3(OH) is the same as that of the 1665/1667-MHz emission

[en] Two outstanding problems in the interpretation of OH masers are their narrow linewidths, and the rare occurrence of Zeeman pairs. In the Cook-Shklovskii model, if the magnetic field and the bulk velocity of the gas along the line of sight vary, the gradients in Zeeman shift and Doppler shift may match to keep only one component in resonance with the molecules for a significant distance. With this interpretation a Zeeman pair would be expected from a given region only when the relevant gradients are negligible. Some implications of this model were studied. The condition under which only one Zeeman component may be seen was derived and was shown to be satisfied at least for the source W3(OH). The model does not allow any line-narrowing but implies a broadening of features during saturated growth

[en] There is reason to believe that the physical conditions in many astrophysical masers are far from homogeneous. In particular, if the maser pump involves the absorption of infrared photons, the pump rate may vary rapidly (perhaps exponentially) across the cloud. The consequences of such variation of the pump rate for the maser radiation are calculated, and it is shown that there are substantial asymmetries in the output of the maser. A general result is that the maser radiation is preferentially emitted back toward the source of pump radiation. The implication of this result for the interpretation of the circumstellar 1612 MHz OH masers is briefly discussed. 14 references

[en] Aleksandr Mikhailovich Prokhorov was a Russian physicist, academician, one of the originators of quantum electronics, laser physics and laser technologies, winner of the 1964 Nobel Prize in Physics 'for fundamental work in the field of quantum electronics, which has led to the construction of oscillators and amplifiers based on the maser – laser principle' (shared with N.G. Basov and Ch.H. Townes), Lenin Prize and State Prize winner and twice Hero of Socialist Labour. (personalia)

[en] Experiments planned for the characterization of the 35GHz girotron, which is being built at the Plasma Laboratory of INPE, are described. The methods of the measurements are presented and the required instrumentation and devices are specified. Special attention is given to the measurement techniques of the resonator electric field profile. (author)

[en] Very long baseline interferometry, or VLBI, is the observing technique yielding the highest-resolution images today. Whilst a traditionally large fraction of VLBI observations is concentrating on active galactic nuclei, the number of observations concerned with other astronomical objects such as stars and masers, and with astrometric applications, is significant. In the last decade, much progress has been made in all of these fields. We give a brief introduction to the technique of radio interferometry, focusing on the particularities of VLBI observations, and review recent results which would not have been possible without VLBI observations

[en] We present Submillimeter Array 1.3 mm waveband continuum and molecular line observations of the HH 80-81 high-mass star-forming region. The dust continuum emission reveals two dominant peaks, MM1 and MM2, and line emission from high-density tracers suggests the presence of another core, MC. Molecular line emission from MM1, which harbors the exciting source of the HH 80-81 radio jet, yields a hot molecular core at a gas temperature of 110 K. The two younger cores, MM2 and MC, both appear to power collimated CO outflows. In particular, the outflow arising from MM2 exhibits a jet-like morphology and a broad velocity range of 190 km s^-1. The outflow contains compact and fast moving molecular clumps, known as 'molecular bullets', first discovered in low-mass class 0 protostellar outflows. These 'bullets' cannot be locally entrained or swept up from the ambient gas, but are more likely ejected from the close vicinity of the central protostar. The discovery of this remarkable outflow manifests an episodic, disk-mediated accretion for massive star formation.