The speckle polarimeter of the 2.5-m telescope: Design and calibration

The speckle polarimeter is a facility instrument of the 2.5-mSAIMSU telescope that combines the features of a speckle interferometer and a polarimeter. The speckle polarimeter is designed for observations in several visible bands in the following modes: speckle interferometry, polarimetry, speckle polarimetry, and polaroastrometry. In this paper we describe the instrument design and the procedures for determining the angular scale of the camera and the position angle of the camera and the polarimeter. Our measurements of the parameters for the binary star HD 9165 are used as an example to demonstrate the technique of speckle interferometry. For bright objects the accuracy of astrometry is limited by the error of the correction for the distortion caused by the atmospheric dispersion compensator. At zenith distances less than 45? the additional relative measurement error of the separation is 0.7%, while the additional error of the position angle is 0.3°. In the absence of a dispersion compensator the accuracy of astrometry is limited by the uncertainty in the scale and position angle of the camera, which are 0.15% and 0.06°, respectively. We have performed polarimetric measurements of unpolarized stars and polarization standards. The instrumental polarization at the Cassegrain focus in the V band does not exceed 0.01%. The instrumental polarization for the Nasmyth focus varies between 2 and 4% within the visible range; we have constructed its model and give a method for its elimination from the measurements. For stars with an intrinsic polarization of less than 0.2% during observations at the Cassegrain focus the error is determined mainly by the photon and readout noises and can reach 5 × 10^?5.     

The Investigation Results of the April 12, 2014, <Emphasis Type="Italic">M</Emphasis> = 4.5 Primorye Earthquake (Far Eastern Russia)

Primorye is a region with quite moderate shallow seismicity which has been insufficiently investigated so far in this respect. Based on the obtained instrumental data of regional seismic networks and macroseismic data collected in southwestern Primorye on the crustal earthquake with M = 4.5 occurred on April 12, 2014, we have first succeeded in determining the hypocenter parameters and the focal mechanism of the mainshock of this shallow earthquake and estimating the hypocenter parameters of the following aftershock.     

http://www.sciencedirect.com/science/article/pii/S1674987114000449

We review petrologic observations of reaction textures from high-grade rocks that suggest the passage of fluids with variable alkali activities. Development of these reaction textures is accompanied by regular compositional variations in plagioclase, pyroxenes, biotite, amphibole and garnet. The textures are interpreted in terms of exchange and net-transfer reactions controlled by the K and Na activities in the fluids. On the regional scale, these reactions operate in granitized, charnockitized, syenitized etc. shear zones within high-grade complexes. Thermodynamic calculations in simple chemical systems show that changes in mineral assemblages, including the transition from the hydrous to the anhydrous ones, may occur at constant pressure and temperature due only to variations in the H2O and the alkali activities. A simple procedure for estimating the activity of the two major alkali oxides, K2O and Na2O, is imple- mented in the TWQ software. Examples of calculations are presented for well-documented dehydration zones from South Africa, southern India, and Sri Lanka. The calculations have revealed two end-member regimes of alkalis during specific metamorphic processes： rock buffered, which is characteristic for the precursor rocks containing two feldspars, and fluid-buffered for the precursor rocks without K-feldspar. The observed reaction textures and the results of thermodynamic modeling are compared with the results of available experimental studies on the interaction of the alkali chloride and carbonate-bearing fluids with metamorphic rocks at mid-crustal conditions. The experiments show the complex effect of alkali activities in the fluid phase on the mineral assemblages. Both thermodynamic calculations and experiments closely reproduce paragenetic relations theoretically predicted by D.S. Korzhinskii in the 1940s.     

Performance analysis of differential speckle polarimetry

We consider a method for obtaining information on polarization of astronomical objects radiation at diffraction limited resolution—differential speckle polarimetry. As an observable we propose to use averaged cross spectrum of two short-exposure images corresponding to orthogonal polarizations, normalized by averaged power spectrum of one of images. Information on polarization can be extracted if object under study can be described by model with several parameters. We consider two examples: pointlike source whose photocenter position depends on orientation of passing polarization and exozodiacal dust disc around a star. In first case the difference between photocenter positions can be measured with precision of 8 µas for 2.5-m telescope and 1.2 µas for 6-m telescope for object V = 13 ^m . For second example method allows detection of discs around central star of V = 1 ^m with fractional luminosities of 1.8 × 10^?5 and 5.6 × 10^?6 for 2.5- and 6-m telescope, respectively.     

Participation of hydrothermal fluids in the formation of deposits of the proterozoic Udokan-Chineysky ore system

Numerous Cu deposits of the Udokan-Chineysky ore district (Udokan deposit of cupriferous sandstones, deposits of the Chineysky pluton, etc.), which occur in sedimentary and igneous rocks, are similar in many genetic features. One of these features is the similar parameters of fluid inclusions (hydrothermal fluids) in quartz of the Udokan deposit, rich chalcopyrite ores from the Rudnyi (Rudnyie deposit, and veins of the Pravoingamakitsky deposit studied previously. Fluid inclusions have the same range of high salinity and homogenization temperatures. These studies combined with geological data allow us to consider the formation of contact sulfide ores from the Chineisky pluton and Pravoingamakitsky and Udokan deposits as a common compound fluid-magmatic ore-generating system. The sedimentary rocks primarily enriched in chalcopyrite, pyrite, and pyrrhotite of the entire section of the Udokan complex served as the host media for the hydrothermal fluids and deposits of various scales.     

Biogeochemistry of calcium and strontium in the landscapes of eastern Transbaikalia

This paper reports data on the contents and ratios of Ca and Sr in the soils, waters, and plants of eastern Transbaikalia and the Baikal region. The contents of Ca in the soils, waters, and plants of endemic areas affected by Urov disease approach those in objects from control areas. The contents of Sr in the soil–plant complex of the Urov biogeochemical province are relatively high and show spotted distribution, which is related to the landscape-geochemical characteristics of the region. It was found that the Ca/Sr values in the soils of a number of areas unaffected by Urov disease of animals and humans fall mainly within 11–236 (53 ± 24 on average). In the soils of endemic regions in eastern Transbaikalia, Ca/Sr ranges from 2 to 98 (36 ± 11 on average). The hay crop of meadow plants show Sr contents of 72.8 ± 31.6 mg/kg (endemic region) and 36.6 ± 15.7 mg/kg (control areas) and Ca/Sr values of 250 ± 115 and 525 ± 382, respectively. The elevated Sr content in the soils and plants of the endemic region is considered as a factor of ecological risk.     

Experience in seismic signal recording using broadband electrochemical seismic sensors

Development and application of broadband seismic sensors, namely velocimeters of electrochemical type (chemotrons), are considered. The principle of operation and design of modern electrochemical (molecular-electronic) converters of seismic signals for linear and rotary motions are described. The data on metrological certification and prolonged trials of these seismic sensors on test benches are presented. Their advantages as compared to stationary broadband seismic sensors of electrodynamic type lie in impact immunity, high power supply efficiency, operability at large inclinations and in a wide temperature range. Comparative analysis of records of the Sichuan Earthquake (China, May 12, 2008) obtained in Moscow on a test bench at the Institute of Physics of the Earth of the Russian Academy of Sciences with help of an electrodynamic seismic sensor and on a test bench at the Design Bureau of Oceanological Equipment of the Russian Academy of Sciences with the help of an electrochemical sensor is presented in conclusion.