Next: Estimating the angle Up: Wavelength Calibration Previous: General Description . The wavelength calibration involves a physical equation, the echelle relation and regression analysis to achieve estimates of the dispersion relation. Provided that the echelle dispersion is performed with a grating, any echelle spectrum can be calibrated usually with four lines used as pre-identifications and a catalog of laboratory wavelengths associated to the calibration lamp. ... Echelle Relation) . ...

... A universal physical relation for quasars . ... Harvey Tananbaum and his collaborators have first observed a relation between the soft X-ray and the optical/ultraviolet emission in AGN in 1979. Such relation is nonlinear, and it is usually parameterized as dependence between the logarithm of the monochromatic luminosities at 2500 †Е ( L 2500†Е ) and 2 keV ( L 2keV ) . ... Yet, the dispersion along the L 2500†Е тАУ L 2keV relationship is found to be rather high, typically ~0.35тАУ0.4 in log units. ...

... Mindful of these biases, I can now explore the relations between the measured rotation periods and various other observables. The hypothesis behind monitoring stellar variability is that active stars have asymmetric spot distributions on their photospheres. ... They found that only stars with rotation periods greater than seven days show variations greater than 0.4 magnitudes at I. Bouvier et al . ... 1993a) demonstrated a relation between X--ray flux and spectral type in ZAMS stars. ...

... All the information about the propagation of a given plasma wave mode is contained in the appropriate dispersion relation, which relates the angular frequency w to the wave number k (magnitude of the propagation vector k ). ... Phase velocity . ... Group velocity . ... Wave propagation can also be described using diagrams called phase velocity or wave normal surfaces , which give the variations of the magnitude of the phase velocity of plane waves with respect to the magnetic field direction: . ...

PEGASE: Project de'Etude des Galaxies par Synthese Evolutive (by Damien Le Borgne and Brigitte Rocca-Volmerange) . Galaxy colours (by Robin Stevens) . ... Images of radio galaxies and quasars mapped at VLA . Atlas of radio galaxies in 3CRR sample (images, description, classification, etc.) Radio Galaxy and Quasar Images at Other Sites by A.Bridle . ... Radio galaxies in Abell clusters . ... Digitized Sky Survey images . Faint Images of Radio Survey at Twenty-cm at VLA . ...

... The concepts of Fourier frequency and wavelet duration are obviously related. ... Among many sensible definitions, we chose to require that the peak of the wavelet mean spectrum should be matched with the singularity of the Fourier transform of the cosine wave. Then, it can be shown that the frequency of the cosine is related to the wavelet duration by the relation . ... The ambiguous definition of the duration of an event is common to the sizing of any object of irregular shape. ...

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. Photographs of the Hubble Space Telescope . James Webb Space Telescope Graphics . Photographs of the Space Telescope Science Institute . Caltech photographs of Edwin Hubble (Copyrighted material) . Photographs of Goddard Space Flight Center . Selected Illustrations (line-art) related to HST . Some HST -Related News Articles and other Media (Copyrighted material) . HubbleSite . HubbleSite Sci-Tech . NASA's Hubble Project . Wikipedia . Zolt Levay , STScI . September 16, 2006

... Pre-university education . ... SSAU History . ... International relations . ... Thus, in different years the University entered into agreements with the universities of China (Harbin Politechnical Institute, Beijing Aerospace University , Beijing Politechnical University , North-West Politechnical University , Bradley University (USA), Sofia Technical University (Bulgaria), Stuttgart Technical University (Germany), Berlin Technical University (Germany), Carlow Technical ...

... The task also issues a number of housekeeping related messages and values and also writes several keywords to the EXPOSURE extension (the information is usually CCD-dependent and it is thus important that it is kept and propagated through the event file processing chain). ... Filter: the filter wheel position is derived from the position sensor potentiometer (housekeeping column F1122 contained in the main periodic housekeeping file PNPMH1 , HK mnemonic H_CE_FWSPOT). ...

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 ...

Hide Zen home . ... Based on a single concept x2013; a 2 dimensional table with rows & columns called a relation . ... each column represents an attribute . A relational database contains one or more relations, or tables. tuples have no particular order . ... all values belonging to a particular attribute are from the same domain . ... A relational model of data for large shared data banks". ... 0 Comments on relation featur?s This page is read-only View other revisions Administration . ...