[en] Sky maps of over 1,000 brief x-ray transients or flares observed by the Vela 5A and 5B satellites are presented. These results are published in preliminary form as a possible aid for planning the observational programs of currently operating x-ray satellites

[en] The flare stars in the Pleiads were investigated. The observations were carried out from the second part of 1972 to the beginning of 1973. Data on 9 new and 9 repeat flares are given. The new data are compared with those obtained previously

[en] The positions of 22 UV Ceti-type flare stars were surveyed with the Arecibo radio telescope at a frequency of 430 MHz in a search for close and possibly physically associated radio sources. The active flare stars AD Leo and CN Leo have radio sources within two arc minutes. The probability of this resulting from a random association is estimated to be of the order of 5 percent. While far from convincing, this probability is small enough to retain interest in the problem. A definitive test of the nature of the CN Leo association is discussed

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[en] In order to observe flare stars of nearby open clusters and star associations, astronomers of many countries employ the same method. This method of photographic photometry by wide-field telescopes is only partly standardized. Differences in the various steps of the method, in the fields of view of the telescopes and in sky brightness of the observatories participating in the common work can make the statistical evaluation of the results more difficult and can lead to delusive conclusions. A critical evaluation of the problematic points of the observations and reports is given. Statistical results of flare star observations in the Pleiades field made during the past two decades are summarized. It is shown that the estimated number of flare stars in the region observed as published by scientists of the Byurakan Astrophysical Observatory is too low. A model of the flare star system of the field is presented. It is composed of seven differently populated subsystems with various mean flare frequencies. The strength of this model is shown on the basis of the photographic observations of the last decade. The total number of flare stars in the Pleiades field is estimated to be higher than 2500 and the expected number of flare-up observations in order to discover all of them is given (nearly 23000). (author)

[en] Results of polarimetric and photometric observations of flare EV Lac and AD Leo stars are presented. In the course of 89.5 hrs observation flares have been detected observation summary and light curves of which are given in a table and in figures. The results of polarimetric observations in the time of flares have not differed from polarization results in tranquil state of the stars and are in the limits of measurement error

[en] The analytic time-representation of the multiplicity of flares in stellar aggregates based on observational data at present is given under the condition of independency of flares from each other. They are exactly approximated by two ''Poisson'' groups with stars in each of them having the same frequency: N₁=670, ν₁=1.1 flares at all observational time, N₂=60, ν₂=9 - for Pleiades, and by one Poisson process with N=1250, ν=0.49 - for Orion, N=330, ν=0.37 - for the Dark Nebulae of Taurus. The total number of fkare stars in the Pleiades is nearly equal or less than 750

[en] The UV Ceti flare stars YZ CMi, BD+16⁰2708, EV Lac, and AD Leo were monitored photoelectrically for flare activity with the 76 centimeter reflecting telescope of the University of Florida's Rosemary Hill Observatory. Observations were carried out from January, 1973 to April, 1975. The instrumentation allowed simultaneous readings to be taken at 3500, 4632, and 6496A with a time resolution of 2 seconds. A total of 15 major events were observed, with 14 of these being observed in all three colors. All events showed the classical fast rise and slower decline that is typical of this type of activity. One event showed peculiar behavior in the red bandpass that may indicate strong dependence of the flare light in some cases on line emission. The data were applied to the fast electron model of flare activity proposed by Gurzadyan. Several serious inconsistencies in the theory were found that would not have been evident in single-channel monitoring. No event could be fitted in all three colors using consistent values of the unknown parameters in the theory. The most serious deficiencies in the theory were the wavelength dependence of the optical depth of the electron cloud and the lack of treatment of line emission behavior. Differential color indices for flare light are calculated and are shown to be essentially constant throughout the entire event for the stronger flares. A color-color plot of the flare light at maximum reveals that 11 of the flares show a linear relation. This relation indicates that the smaller the u-b index, the larger is the b-r index. This is probably directly involved with line emission during flare events. Future research possibilities are discussed, with spectroscopic studies and simultaneous multicolor observations being stressed