A method of comparison of exact and asymptotic wave field computations     

Alexei P. Kiselev  Ilya D. Tsvankin 《Geophysical Journal International》1989,96(2):253-258

Summary. A method of comparison of exact numerical computations with an asymptotic ray series expansion consisting of the two first terms is proposed. The method makes it unnecessary to derive complicated explicit expressions for the second leading term of the ray series.
As a practical example we consider the anomalous PS arrival generated in the case of a near-vertical incidence of a spherical P wave on a solid/solid boundary. The areas in which the PS wave may be described by two leading terms of the ray series expansion are marked and deviations from the ray theory are analysed.  相似文献   

Stratigraphy of the Bathonian-Callovian boundary deposits in the Prosek section (Middle Volga Region). Article 1. Ammonites and infrazonal biostratigraphy     

D. N. Kiselev  M. A. Rogov 《Stratigraphy and Geological Correlation》2007,15(5):485-515

In European Russia, the most complete succession of Boreal sediments of the terminal Bathonian and lower Callovian is exposed near the Prosek Settlement. After its revision, the infrazonal division of the upper Bathonian and lower Callovian and position of the Bathonian-Callovian boundary are difined more carefully. The Calyx Zone and bodylevskyi Biohorizon are established in the upper Bathonian. The base of the lower Callovian is defined at the first occurrence level of Macrocephalites jacquoti. Based on four successive ammonite assemblages occurring in lower part of the Elatmae Zone, the breve, frearsi, quenstedti, and elatmae biohorizons are identified. The joint occurrence of Boreal, Subboreal, and Tethyan ammonites in the section facilitate its correlation with the other sections of the Panboreal paleobiogeographic superrealm.  相似文献   

Early Cambrian magmatism in the northeastern Siberian Craton (Olenek Uplift)     

A. I. Kiselev  B. B. Kochnev  V. V. Yarmolyuk  K. N. Egorov 《Doklady Earth Sciences》2015,465(2):1218-1223

The Vendian–Lower Cambrian tectonomagmatic activation took place in the northeastern Siberian Craton, within the Olenek Uplift and in the Kharaulakh segment of the Verkhoyansk fold-and-thrust belt (the lower reaches of the Lena River). The Early Paleozoic volcanic activity in the Olenek Uplift is expressed in the form of basitic diatremes, small basaltic covers, and doleritic dikes and sills intruding and covering the Upper Vendian carbonate deposits. The material specificity of the Lower Cambrian basites and their mantle sources, jointly with the Vendian–Cambrian sedimentation history, gives reason to consider the Lower Cambrian riftogenesis and the associated magmatism as a consequence of the plume–lithosphere interaction in the northeastern Siberian Craton.  相似文献   

Photographic observations of visual double stars at Pulkovo: Digitization,measurement, and calibration     

I. S. Izmailov  E. A. Roshchina  A. A. Kiselev  T. P. Kiseleva  O. A. Kalinichenko  O. P. Bykov  O. V. Kiyaeva  L. G. Romanenko  N. A. Shakht  K. L. Maslennikov  T. A. Vasil’eva 《Astronomy Letters》2016,42(1):41-54

We present the results of determining the relative positions of 359 pairs of stars. More than 6000 photographic plates were obtained in 1960–2007 at the 26-inch refractor of the Pulkovo Observatory. The plates have been digitized with a Canon EOS 5D Mark II digital camera and a long-focus Jupiter 21M lens; the scalewas 21 μm/pixel. Themeasurements have been calibrated using a template digitized with the Belgian high-precision ROB Digitizer. The results have been thoroughly investigated for systematic errors. We have studied the scale of the 26-inch refractor and revealed its temperature and time dependences. The application of a new digitization, measurement, and calibration technique has allowed the accuracy to be increased compared to the past measurements. The single-exposure measurement accuracy is within the range from 2 to 70 mas, on average, 28 mas in both coordinates. The errors of the yearly mean positions are, on average, 8.7 mas in the angular separation and 0.05?. in the position angle.  相似文献   

Results of the Photometric Observations of the NEA (2100) Ra-Shalom During an Encounter in 2019     

Abdulloev  S. Kh.  Kiselev  N. N.  Shamsiddinov  Sh. Sh. 《Solar System Research》2021,55(5):398-401

Solar System Research - This paper presents the results of the photometric CCD observations of the NEA (2100) Ra-Shalom carried out on August 24–29, 2019, at the 1-m telescope of the Sanglokh...  相似文献   

Orbit determination and estimate of the component masses     

N. A. Shakht  D. L. Gorshanov  E. A. Grosheva  A. A. Kiselev  E. V. Polyakov 《Astrophysics》2010,53(2):227-236

  相似文献   

Phase functions of polarization and brightness and the nature of cometary atmosphere particles     

N.N. Kiselev  G.P. Chernova 《Icarus》1981,48(3):473-481

The dependence of brightness and polarization of cometary on the phase angle is studied. The similarity between the phase curves of comets, minor planets, and the zodiacal cloud is pointed out. The dependence found correspond to dielectric particles with dimensions greater than 1 μm.  相似文献   

Results of astrometric observations of Jupiter’s Galilean satellites at the Pulkovo Observatory from 1986 to 2005     

T. P. Kiseleva  A. A. Kiselev  O. A. Kalinichenko  N. A. Vasilyeva  M. L. Khovricheva 《Solar System Research》2008,42(5):414-433

The results of photographic observations of Jupiter’s Galilean satellites made with the 26-inch refractor at the Pulkovo Observatory from 1986 to 2005 are given. Satellite coordinates with respect to Jupiter and the mutual distances between the satellites have been determined. A scale-trale technique that does not require reference stars for the astrometric reduction of measurements has been used. The effect of the Jupiter phase has been taken into account in the jovicentric coordinates. The observation results have been compared with a modern theory of the Galilean satellites’ motions. Systematic observation errors depending on the observation technique have been studied. The intrinsic observation accuracy in the random quotient is characterized by the values 0.041″ over X and Y. The external accuracy of the relative Galilean satellite coordinates determined by comparing the observations with modern ephemerides turned out to be equal to 0.165″, 0.213″ for the Jovicentric coordinates and 0.134″, 0.170″ for the “satellite-satellite” coordinates. The highest accuracy of the relative satellite coordinates is reached at small distances between the satellites which are less than 100″: the corresponding mean-square errors of one observation are equal in to the external convergence to 0.050″, 0.070″. The results of photographic observations have been compared with the first CCD observations of the Jupiter satellites made in 2004 with the 26-inch refractor.  相似文献   

Light Scattering by Aggregate Particles Comparable in Size to Wavelength: Application to Cometary Dust     

Petrova  E. V.  Jockers  K.  Kiselev  N. N. 《Solar System Research》2001,35(1):57-69

Many naturally occurring particles (including, most likely, cometary dust) have an aggregate structure. We study the scattering properties of polydisperse independent aggregate particles (clusters) comparable in size to visible wavelengths. The sizes of the monomers constituting a cluster play a significant role in forming the angular dependences of intensity and linear polarization of the scattered light. Irregularly structured aggregates composed of a moderate number of spheres (<50) with size parameters 1.3–1.65 exhibit properties typical of cometary dust particles: a slight increase in backscattering intensity, a negative polarization at small phase angles, an inversion phase angle close to the observed one, an increase in brightness, and a linear polarization with increasing wavelength. In this case, the imaginary part of the refractive index for particles can increase with decreasing wavelength in the visible spectral range, which is typical of silicates with an admixture of iron or organic material. The spectral dependence of extinction efficiency for aggregates is less steep than that for equivalent spherical particles, and its maximum is shifted to larger size parameters. Therefore, when analyzing extinction measurements, the scatterer shape must be taken into account to avoid underestimation of the scattering-particle sizes.  相似文献   

Properties and Peculiarities of Mercury's Regolith. Disk-integrated Polarimetry in 2000–2002     

Kiselev  N. N.  Lupishko  D. F. 《Solar System Research》2004,38(2):85-92

On the basis of the data from ground-based polarimetric, photometric, and other observations, as well as from space measurements (Mariner 10), we survey the investigations of the properties and peculiarities of Mercury's regolith in detail. We also present the results of our own observations performed during three apparitions of the planet in 2000–2002. An analysis of the published data points to essentially more intensive maturation processes in the Hermean surface regolith compared to that on the lunar surface. In addition, the orbital characteristics of Mercury allow us to suppose that the intensity of its regolith maturation and, therefore, the optical properties of its surface can noticeably depend on the planetocentric longitude. Polarimetric observations of Mercury's surface (the planetocentric longitude range was 265°–330°) carried out in 2000–2002 with a 70-cm reflector actually detected a polarization degree varying with an amplitude of about 1.5%. To ascertain the nature of these variations, additional observations of Mercury in a maximally wide range of planetocentric longitudes of the viewed surface are required.  相似文献