... 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. ...

... The visibility datasets possibly contain correlations for different polarizations and Stokes parameters. There are two basic ways that polarization characteristics can be measured: firstly, two orthogonal feeds can be present on the antennas, and the four different polarization correlations from a baseline can be taken and recorded. ... There are two ways the user can determine which polarizations he or she wants to process, either with the select parameter, or with the stokes parameter. ...

This is a tabulation of interstellar dust scattering properties dertermined from observations of various astrophysical objects (eg., ... Almost all studies in this field aim to determine the single scattering albedo (a) and scattering phase function asymmetry (g = <cos( )>) as different wavelengths. ... Plot Details . ... Plot details links to a page describing the studies included in the plot, the radiative transfer model used in each study, and an ascii listing of data plotted. ...

Observed maximum rotation velocity uncorrected for inclination effect. This quantity is calculated from 21-cm line widths at different levels and/or rotation curves (generally in H_alpha). ... These data are characterized by some secondary parameters: telescope, velocity resolution, level of the 21-cm line width and bibliographic reference. ... we start from a standard sample (a set of measurements giving a large and homogeneous sample). ... HyperLeda . ...

... The initial descriptions of the FITS format provided a simplified method for describing the physical coordinate values of the image pixels, but deliberately did not specify any of the detailed conventions required to convey the complexities of actual image projections. ... They were CRPIX n for the reference pixel location on pixel axis n , CRVAL n for the coordinate value at that pixel, CDELT n for the increment at that pixel in the coordinate value, and CTYPE n for the type of coordinate. ...

This group of four pages describes how the Arecibo 430 MHz radar makes simple measurements in the ionosphere. ... Radar Reflections From the Ionosphere . ... Or How are radio and TV stations like radars?) ... Consider two radio stations located on a mountain transmitting to a nearby city. ... A radar is like a radio station, but it has a receiver that picks up radio waves reflected from objects (targets). ... Although a radio station transmits continously, a radar can transmit short bursts of waves. ...

... The extinction in terrestrial atmosphere. ... A star was observed at different zenith distances during one night at the Engelgardt's Astronomical Observatory in the program of atmospheric extinction study at blue. ... Calculate the air mass for given zenith distances in 1st 54.9 11800 column, and write the result into the 2nd column. ... Spectral observations. ... Calculate the radial velocity Vr of the star on each date, the results of measurements and write calculations into the table. ...

. There are several different shells available for Unix; the most popular are described here. You can use any one of these shells if they are available on your system. And you can switch between the different shells once you have found out if they are available. Bourne shell (sh) . C shell (csh) . TC shell (tcsh) . Korn shell (ksh) . Bourne Again SHell (bash) .

The ESA/ESO Astronomy Exercise Series 2 . The Distance to Messier 100 as Determined by Cepheid Variable Stars . ... The small variations in distance to the individual Cepheid variable stars in the Cloud are negligible compared with the much larger distance to the SMC. ... In this way Cepheid variable stars can be used as one of the 'standard candles' in the Universe that act either as distance indicators themselves or can be used to calibrate (or set the zero point for) other distance indicators. ...

... Future seminars . P a s t seminars . Seminar council . Collective processes and structures in spiral galaxies " . ... A new approach to studying global structures in thin stellar disks, which allows to describe universally both bar and spiral modes, is presented. ... Study of line-of sight velocity maps of gaseous disk in spiral galaxies allows, under some conditions, to reconstruct 3 components of gas velocity in the galactic plane. ...

Atmospheric influence on the different radio-engineering system functioning . ESTIMATION OF ATMOSPHERIC OPTICAL CHARACTERISTICS AND REMOTELY SANSED IMAGE CORRECTION . ... Direct transmittance estimation results for 12 channels of the spectrometer CHRIS. ... We have managed to develop a direct method of estimating the discrete Normalized Atmospheric Point Spread Function (NAPSF) from available images alone, not using any external sources of information about the atmosphere. ... IRE RAS 1996-20 11 ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2000 January 8 . Albert Einstein Describes Space and Time . Explanation: Albert Einstein (1879-1955) is considered by many the greatest astrophysicist and single most significant Person of the 20th Century . ... One reason Einstein was awarded the 1921 Nobel Prize in Physics was to make the prize more prestigious. ... About APOD | ...

Next: When the clock is Up: Keeping Time Previous: The hardware and software . In the Debian system, the system time zone is determined by the symbolic link /etc/localtime љ . ... If it is unset, the system time zone is assumed. ... The date љ command shows the current date and time. ... date љ is also used to set the kernel's software clock: # date 07142157 . ... While each user can have his own time zone, the clock is the same for everyone. date љ only shows or sets the software clock. ...

Astronotes Armagh Planetarium's Stellar Blog! ... Our Galaxy . ... Stars . ... Other Galaxies . ... Light of other eyes, other times: The X-rays and IR radiation making up the image have been travelling for a long time. ... The inspiration here came from a new ESA image of M31, the Andromeda Galaxy, composed from two very different images. ... Our nearest galactic neighbour, the Andromeda Galaxy?s brightness is caused by the hundreds of billions of stars that are contained within. ...

... Science . ... Science Users Information > Data Handling and Products > Data Reduction FAQ > I want to process MOS data of the same target from different nights together - how can I do that? ... Observing Facilities . ... Observing with ESO Telescopes . ... However, if you want to process science data from different nights together you should limit the available calibrations to those from one night as the pipeline assumes that the calibration data were taken without mask movement in between. ...

... A detector map is used to provide a grid of positions over which to calculate and flux weight the ARF. The default detector map is 'flat' which has a weighting of 1.0 for each detector map pixel and is rectangular having sides which just encompass the region specified in the DSS. Only detector map pixels falling within the source region are included in the ARF calculation, e.g. for a circular source box, the pixels in the corners of the detector map will be ignored. ... flat : . ...

... During the analysis of the surveys carried out on RATAN-600, it was found that almost one fifth of the detected sources shows significant radio flux variations. ... We used the data from "Cold" radio surveys carried out with RATAN-600 in 1980-1994 to search for radio sources with significant flux variability. ... On possibility of detection of variable sources using the data of Cold surveys carried out on RATAN-600. ... Detection of Variable Sources Using the Data of "Cold" Surveys. ...

Next: Filtering ROSAT HRI data Up: ROSAT HRI Recipes Previous: Correlating Spectral Data with . Although the spatial variation of the quantum efficiency across the HRI is nominally within 10% for most of the detector, occasionally it may be desirable to flat-field a map with preflight calibration measurements. ... Store the new gain map image using ``blink" in SaoImage. ... The quantum efficiency correction (QEC) is the inverse of the intensity determined from the QE map at the source position. ...

... A three-cell test section roughly representative of the primary mirror was provided for this test by the Steward Mirror Lab. ... Additionally, the tests are intended to determine relative airflow vs. pressure drop characteristics for each of the air flow patterns so the results can be evaluated both as a function of flow rate and of pressure drop along the flow path. ... The bottom (top as installed) was cut out so it could close the chamber for heating and be removed for the cooling tests. ...

Databases (NSDC) of the Natural Planetary Satellites. ... NSDC: Database of astrometric observations of Natural Planetary Satellites . ... They are thoroughly looking for observations in different sources, creating their owndatabases which are then mostly inaccessible to other researchers. ... In the file "content" with explications, the reference is given to the data source as well as the bibliographic reference. ... Data sources. ... Why a specific bibliographic database for Natural satellites? ...