... 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. ...

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): . ...

... It was designed to observe the solar wind approaching Earth, from a position near the Lagrangian point L1, and it is part of the International Solar-Terrestrial Physics (ISTP) Initiative . ... The original plan called for "Wind" to approach its final station over two years, undergoing two close encounters with the Moon to boost its speed. ... If however the object is moving , the encounter is not symmetric, and in the end the spacecraft may have gained or lost speed, depending on its trajectory. ...

... 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...

... It was designed to observe the solar wind approaching Earth, from a position near the Lagrangian point L1, and it is part of the International Solar-Terrestrial Physics (ISTP) Initiative . ... The original plan called for "Wind" to approach its final station over two years, undergoing two close encounters with the Moon to boost its speed. ... If however the object is moving , the encounter is not symmetric, and in the end the spacecraft may have gained or lost speed, depending on its trajectory. ...

... This step is done mostly interactively and uses some basic ad-hoc IDL procedures, mainly for testing and checking of the consistency of the results.Once the observations have been selected and the count spectra extracted, the available spectra of each background level are accumulated. ... Average QUALITY such that QUALITY =0|1 Exposure times are added and the total is written in the EXPOSURE keyword of the header of the output FITS file. Finally, the CCFs are built from these templates. ...

Proposal Identification No.: S2462 Date Received: 2009-Jan-28 13:24:58 Technical Page Proposal Type: General Category: Observation Category: Total Time Requested: Minimum Useful Time: Prop osal Title: ABSTRACT: Urgent Astronomy Solar System 5 Hours Calibration of the Mini-RF Experinent on the Chandrayaan-I Spacecraft We plan to transmit a circularly-polarized signal to calibrate the polarization of the Mini-RF system on the Chandrayaan-I spacecraft. ...

... 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 . ...

... The spectroscopic data were obtained with the 6m telescope of the Special Astrophysical Observatory of Russian Academy of Science (SAO RAS) during run in October 1999. ... The widths of the slit of 1.2 and 2 were used. ... Observations have been conducted mainly under the software package NICE in MIDAS, described by Kniazev & Shergin ([ 1995 ]). ... All primary data reduction was carried out in the standard way, similar to that described in Kniazev et al. ([ 2000b ]). ...

... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . ... The aim is to investigate the existence of propagating waves in the solar chromosphere and the transition region via analyzing the statistical distribution of power in different locations, e.g. in bright magnetic (network), bright non-magnetic and dark non-magnetic (interтАУnetwork) regions, separately. ... We detect the presence of longтАУperiod oscillations with periods between 15 and 30 minutes in bright magnetic regions...

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... 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. ...

Astronomy Picture of the Day . ... 11.10.2000 . ... Credit: Cassini Imaging Team , Cassini Project , NASA Explanation: A new spacecraft has entered the outer Solar System: Cassini . Launched in 1997 and bound for Saturn in 2004, Cassini sent back the above image last week while approaching the giant planet Jupiter . ... October 2000 . ... 1997 1998 . ... Publications with keywords: Jupiter - spacecraft - cassini spacecraft . Publications with words: Jupiter - spacecraft - cassini spacecraft . ...

... Let us first find out which way -- rise in spectral resolution with some loss in the S/N ratio or increase in the S/N ratio with a fixed spectral resolution -- is better for the purpose of reduction of equivalent width determination errors. ... N -- number of counts for 1 ? ... line equivalent width, . ... Thus if the spectral resolution is managed to be increased (i.e. to decrease )without loss in the number of counts falling at 1 ?, the equivalent width measurement error is then proportional to . ...

Next: Reducing 3-mm ATCA observations Up: Reducing 12-mm ATCA observations Previous: Loading data into Miriad: . For 12-mm data, calibration is essentially identical to the centimetre bands. Primary flux calibration can be done using gpboot and observations of 1934-638, in much the same fashion as at the lower frequencies. 1934-638 is about 1 Jy at 12-mm wavelengths: the Miriad calibration software contains a built-in model of 1934-638's change of flux density with frequency. ...

... A radio galaxy is a galaxy that emits an unusually big amount of energy at radio wavelengths. ... Inside of each galaxy with an active nucleus (radio galaxies are among them) there must be a system of a "central machine" responsible for the colossal amount of the emitted energy from radio to gamma ranges. ... Sometimes a radio source in an active galaxy may flare again if the needed conditions appear (a new portion of matter would fall into the furnace of the "central machine"). ...

Estimations of the change of the Sun s mass and the gravitation constant based on high-accuracy observations of planets and spacecraft . ... More than 635 000 positional observations of planets and spacecraft of different types have been used for estimating possible changes of the gravitation constant, the solar mass, and semi-major axes of planets. ... gravitation constant, positional observation, Sun's mass. ...

... 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 . ...

Links on this page are to sites that hold information on the Sun , our nearest star . ... Big Bear Solar Observatory (BBSO) , California, USA. Mauna Loa Solar Observatory (MLSO) , Hawai'i, USA. ... Space Environment Center, Current Solar Images , Boulder, Colorado, USA. ... Solar Data Analysis Center, Latest Images , at GSFC, Maryland. ... NSSDC - National Space Science Data Center, Solar Physics (at GSFC). ... NSSDC - National Space Science Data Center, Space Physics (at GSFC). Back to Links ...

... In order to realize the optimal scientific return from the VLT, ESO has undertaken to develop an end-to-end data flow system from proposal entry to science archive. The VLT Data Flow System (DFS) is being designed and implemented by the DFS Group (ESO Internal access only) in collaboration with VLT Division and Instrumentation Division . ... VLT Control System Interface . ... OBs are the quantum of data that flows within the DFS, collecting state, data and status information as they flow. ...