... 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 . ...

GRANAT is the Russian x-ray sattelite launched to the high apogee orbit (200,000 km) and operated almost for 10 years (1989 -1999) , carrying out four major instruments: French SIGMA coded-mask hard x-ray telescope (30-1000 keV), Soviet ART-P coded-mask telescope (2??-60?? keV), all-sky monitor WATCH (6-150 keV), and a gamma-burst detector PHEBUS . ... Since September 1994, GRANAT is in the survey mode. ... Explore pages devoted to individual GRANAT instruments (including main scientific results): . ...

... Polarization observations require three or more images with the polarizing filter spanning a large range of position angles on the sky. For WFPC2, this may be achieved by using different quads of the polarizing filter (each quad being oriented 45 degrees to the others), by rotating the spacecraft though different angles, or by a combination of these methods. Rotating the spacecraft through use of ORIENTs provides the simplest calibration, as a single polaroid can be used for all images. ...

Magnetic field measurements onboard the Interball Tail spacecraft are carried out by the FM-3I instrument which consists of two flux-gate magnetometers covering two different ranges: [-200, +200] nT and [-1000, +1000] nT. Besides scientific goals, the FM-3I experiment data is used to perform the attitude control of the Interball Tail spacecraft. ... August 22, 1995 . ... October 18, 1995 . Top of the page . ... Back to the Interball Home Page . ...

... A further spin off of this project is that more reliable pointing information for all exposures is provided. In 1995 the ST-ECF introduced, along with the CADC, the re-calibration on-the-fly (OTF) of archived HST exposures. ... By correlating the HST Mission Schedule and the time-tagged engineering telemetry data stream downloaded from HST it is possible to reconstruct with great accuracy the pointing sequence of any given scientific observation. ... taken within the same HST visit . ...

... 8, ``Celestial Mechanics'', 2002 Station coordinates from observations of DORIS system TOPEX/Poseidon satellite M. V. Vasiliev, E. I. Yagudina Institute of Applied Astronomy, St. Petersburg, Russia The satellite system DORIS (Doppler Orbitography and Radiopositioning In­ tegrated by Satellites System) is the effective means of space geodesy and geody­ namics. ... Along with SLR, GPS observations of DORIS system are used also for EOP parameters de­ termination. ...

Subject of Celestial Mechanics. ... Differential Absolute Coordinates Equations of the Problem. ... General Integral of Non-Perturbed Motion. ... General Equation of Non-Perturbed Orbit. ... Other Integration Methods of Non-Perturbed Motion Differential Equations; Bine Equation for Case of Non-Perturbed Motion. ... Ellipsical Motion, Kepler Equation. ... Motion Differential Equations in Absolute Coordinates. ... Equation of System of Bodies Motion in Barycentric Coordinates, in Relative Coordinates. ...

Pulkovo NEO Page . ... Instrumentation and Observations . ... This Windows application serves for determination of spherical coordinates and magnitudes of the objects. ... The objects coordinates are referred to the system of chosen star catalog. ... 2. choice of reference stars with mouse, . 3. measurement of rectangular frame coordinates of objects and reference stars taking account of predefined background parameters, . 4. calculation of the spherical coordinates of objects. ...

The INTERBALL space mission ( INTERBALL-1 with its subsatellite MAGION-4 in orbits with an apogee of 30 Re, and INTERBALL-2 with its recently reactivated MAGION-5 subsatellite in orbits with an apogee of 4 Re geocentric) continue to conduct important measurements in the solar wind, magnetosheath, magnetotail, magnetopause and above the auroral region. ... Plasma Boundaries in Near-Earth Space . ... Now we announce that online ABSTRACT submission is available at the SYMPOSIUM home page . ...

... Tonight's Sky . ... SUN MOON MERCURY VENUS MARS, JUPITER SATURN . ... Observing . ... Astronomy for Kids . ... MAVEN spacecraft returns first Mars observations . ... NASA s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft has obtained its first observations of the extended upper atmosphere surrounding Mars. ... MAVEN is the first spacecraft dedicated to exploring the tenuous upper atmosphere of Mars. ... Only registered members of Astronomy.com are allowed to comment on this article. ...

... They are concerned with Attitude Control System of the spacecraft, satellite visibility from tracking stations, limits on the satellite autonomous operations during the orbit, and needs for auxiliary operations with the spacecraft. ... Among the operational constraints the most important one is the number of programmed slews per orbit, which determines the maximum number of radio sources to be observed during one orbit. ... System temperature (K) . ... Progress of the RadioAstron Project in Pictures...