... The most precisely determined characteristic for accreting neutron stars (NS's) is their period. ... Period changes show fluctuations. ... Some applications of stochastic processes in astrophysics especially in accreting systems were discussed in Lipunov (1987),Hoshino Takeshima (1993) and Lipunov (1992).In Hoshino Takeshima (1993) the authors, using simple models of MHD turbulence, try to explain aperiodic changes in X-ray luminosity of X-ray pulsars. ... Here, -constant angular momentum. ...

... They were determined as a result of orbit improving on the base of all kinds of optical observations available in the catalog of observations of the Minor Planet Center on March 16, 2014 (radar observations have not been used at this stage). ... As the MPC orbits do not all were improved simultaneously with EMP orbits, only 383866 sets of elements were used for data comparison (for selected sets of elements process of improvement had started with the use of the same observations). ...

THE PHOTOMETRIC RESEARCHS OF THE MERCURY'S SURFACE BY MEANS OF DIGITAL MODELS. ... The surface brightness of Mercury was measured Danjon (1933, 1949, 1953) and Harris (1961) in phase angle 3o-123o. The analysis of the various data of the integral photometric gives the results of determination of the main photometric constants for Mercury. ... THE PHOTOMETRIC RESEARCHS OF THE MERCURY'S SURFACE: S.G. Pugacheva The surface brightness of the Mercurian images was established on the geologic map Mercury. ...

... The absolute flux calibration of NICMOS will be calculated from observations of standard stars with known flux distributions F( ). ... In order to expand the set of IR standard stars in the appropriate flux range for NICMOS, M. Rieke, R. Thompson, and collaborators at the University of Arizona are making photometric observations of solar-analog stars, which will be used to normalize the solar spectrum to the observed IR magnitudes. ... Relative flux references accurate to 1.5% for standard...

Institute of Applied Astronomy Russian Academy of Sciences Method of Determining the Orbits of the Small Bodies in the Solar System Based on an Exhaustive Search of Orbital Planes Dmitrii Vavilov, Yurii Medvedev Introduction to the problem: Let we have n 3 positional observations of a body: points in time ( = 1, ) , right ascensions , and declinations . ... Determination of the orbit using the Gauss method of determining orbital elements based on two heliocentric positions and points in time. ...

... Categories: calibration GPDOF estimates the likely error in a calibration solution, by calculating the errors in the "Degrees-of-Freedom" (dofs) of an interferometer. This is useful for calibration of high-precision circular polarization observations. ... Finally, GPDoF calculates the std and standard error of the derived dofs, which you can use to estimate the errors in the Stokes V of a target observation. ... GPDoF estimates the std and standard error in the dofs. ...

... The HST uses an onboard model of its orbit to perform in real-time various control functions relating to spacecraft operations and observation support. ... New coefficients for the ephemeris are updated every other day, and are archived as FITS keywords for each HST observation data set. Using these coefficients,an observer can perform a variety of calibration and characterization calculations relating to the orbital position and velocity of the telescope. ...

Next: Primary Catalog Up: Observations and Analysis Previous: Source Positions . ... This energy selection allows direct comparison with previous EGRET, COS-B and SAS-2 results. ... The energy spectra shown in the catalog are taken largely from previous EGRET publications (or those currently in the publication process), which discuss the details of source identifications, time variability, and energy spectra. ... Such sources are identified in the catalog. ...

... The experience of determination of the link between radio sources and dynamical reference frames is presented. To obtain this connection we used a series of very long baseline interferometry (VLBI) observations of the spacecraft Phobos-2 and angularly nearby quasars. ... The dynamical reference frame is determined by equator and equinox of these ephemerides. ... References . ... The relative orientation of the radio and dynamical reference frames can be described by a sequence of three rotations . ...

... The accuracy of calculation of both INTERBALL spacecraft (SC) motion has been estimated at the IKI. ... The 30 days measuring intervals were used during the Tail probe (TP) orbital data treatment, and 15 days intervals - during the Auroral probe (AP) orbit determination. ... http://www.iki.rssi.ru/vprokhor/indap.htm for the Auroral probe; . http://www.iki.rssi.ru/vprokhor/indtp.htm for the Tail probe . ... http://www.iki.rssi.ru/vprokhor/ssc.htm , or http://www.iki.rssi.ru/vprokhor/amisan.htm . ...

... Based on the measurements of the Stokes parameters in the continuum and in the broad 0.6563 nm hydrogen emission line obtained with the 6-m telescope for the Seyfert galaxy Mkn 6, secular variability of the hydrogen line profile polarization was discovered; a time lag of less than 2 days between the continuum flux and the polarized continuum emission was determined which corresponds to the size of the region where the polarization of the continuum occurs, less than 0.001 pc. ...