Variations in exospheric density at heights near 1100km, derived from satellite orbits

In an earlier paper, values of exospheric density were obtained from the orbit of Echo 2 for the years 1964–1965. The results indicated a semi-annual variation in density by a factor of between 2 and 3, considerably larger than predicted by existing atmospheric models.

These studies have now been extended to the beginning of 1967, using both Echo 2 and Calsphere 1, to show how the density is responding to increasing solar activity. Variations in density during 1964 have been analysed in more detail. The long-term variation associated with the solar cycle and the short-term variations associated with magnetic and solar disturbances agree with the variations expected on the basis of current models. The semi-annual variation is persisting to higher levels of solar activity, and although its amplitude is diminishing the factor of variation was still 1.6 in 1966.     

Stellar and solar flares

Some ideas are developed concerning solar flares which have been presented earlier by the author (Schatzman, 1966a). Emphasis is laid on the problem of energy transport; from the energy supply to the region of the optical flare, on the storage of low energy cosmic ray particles in a magnetic bottle before the beginning of the optical flare, and the mechanism which triggers both the optical flare, and the production of high-energy cosmic rays. The relation between solar and stellar flares is considered.Lecture given at Goddard Space Flight Center, November 4, 1966.     

The limits of validity of the Frequency Ratio Method: The particular case of γ Doradus stars

This work provides a general vision of the limits of validity of the Frequency Ratio Method applied to the g‐mode pulsators in asymptotic regime, the γ Doradus stars. In particular, the work is mainly focused on the role of rotation which is found one of the most important source of uncertainty of the method. The particular case of the moderately rotating γ Doradus star HD48501 is discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Closed-form solution of P4P or the three-dimensional resection problem in terms of Möbius barycentric coordinates

 The perspective 4 point (P4P) problem - also called the three-dimensional resection problem - is solved by means of a new algorithm: At first the unknown Cartesian coordinates of the perspective center are computed by means of M?bius barycentric coordinates. Secondly these coordinates are represented in terms of observables, namely space angles in the five-dimensional simplex generated by the unknown point and the four known points. Substitution of M?bius barycentric coordinates leads to the unknown Cartesian coordinates (2.8)–(2.10) of Box 2.2. The unknown distances within the five-dimensional simplex are determined by solving the Grunert equations, namely by forward reduction to one algebraic equation (3.8) of order four and backward linear substitution. Tables 1.–4. contain a numerical example. Finally we give a reference to the solution of the 3 point (P3P) problem, the two-dimensional resection problem, namely to the Ansermet barycentric coordinates initiated by C.F. Gau? (1842), A. Schreiber (1908) and A.␣Ansermet (1910). Received: 05 March 1996; Accepted: 15 October 1996     

Solving the problem of shock wave attenuation in an obstacle during a contact explosion of a high-energy material charge

A problem of estimation of shock wave attenuation in an obstacle under an explosion of a high-energy material (explosive) charge on its surface is considered. An algorithm for its solution is proposed using the analytical and semiempirical dependences generally recognized in explosion physics.     

Stochastic variability in the atmospheric activity of Jupiter

The atmospheric activity of Jupiter exhibits quasi-periodic character attributed to the stochastic nature of the involved mechanisms. Periodicities between 4–33 years are obtained employing four spectrum analysis methods, (power spectrum employing the Blackman-Tukey window, maximum entropy, Fourier, autocorrelation), whilst, their significance and their stationarity has been established with the application of general statistical tests (Kolmogorov-Smirnov, one sample and two sample test, randomness test, chi-square, various orders of autoregressive process, analysis of truncated records).Deceased.     

The marine Lockne impact structure, Jämtland, Sweden: a review

The Lockne impact structure in Jämtland (63°00'20"N, 14°49'30"E) formed in the Middle Ordovician at approximately 455 Ma. The structure is a concentric crater with a total diameter of 13.5 km. The impact took place in a marine environment. Seawater played an important role in the cratering process and in crater morphology and the amount of melt remaining in the structure. Seawater rushed back into the crater in a resurge, eroding and redepositing the ejecta among the resurge deposit. Seawater furthermore facilitated the hydrothermal system, which was driven by the residual heat in the structure. The Lockne structure hosts shocked quartz and an iridium anomaly. The rim wall round the crater collapsed in the modification stage of the crater and was annihilated by the resurge. The fractured basement and the impact breccia were initially rich in open cavities. These became partly filled with dominantly calcite. The filling contributed to a low-density contrast, generating a negative gravity anomaly of 22 gu. The gravity model indicates a central uplift and a NW-directed tilt of the structure. This tilt is also seen in the magnetic models. The apparent absence of any impact melt is probably real and related to the environment of impact.     

Search for variable sources using data of “Cold” surveys

We search for variable sources, using the data of the surveys conducted on the RATAN-600 radio telescope in 1980–1994 at 3.94 GHz. To test the radio sources of the RCR (RATAN Cold Refined) catalog for variability, we estimated the long-term variability indices V of the studied objects, their relative variability amplitudes V _χ , and the χ ² probabilities p. Out of about two hundred considered sources, 41 proved to have positive long-term variability indices, suggesting that these sources may be variable. Fifteen objects can be considered to be reliably variable according to the χ ² criterion p > 0.98, three of these sources have χ ² probabilities p ≥ 0.999. The corresponding probabilities for six sources lie in the 0.95 < p < 0.98 interval, and those of the remaining 20 objects in the 0.73 ≤ p < 0.95 interval. Twenty four of 41 objects are variable or possibly variable in the optical range, and five objects are known variable radio sources. We construct the light curves and spectra for the sources with positive long-term variability indices.