... Image formation is typically described as a linear process. ... where, for 2-dimensional systems, the object coordinates are and the image coordinates are . Such a general description of a linear system is termed shift-variant, because the shape of , the impulse response (or point spread function, PSF), might change as the object position, , is shifted. ... Hence, the exit pupil geometry changes with field position, so the system response changes with field position (i.e., is shift-variant). ...

Next: Deconvolution with CLEAN Up: Image Deconvolution Previous: Image Deconvolution . ... The convolution theorem states that the Fourier transform of the sampled distribution (the dirty image, ) is equal to the convolution of the Fourier transform of the true source visibility distribution (the true image, I ) and the Fourier transform of the sampling function (the dirty beam, ): . where indicates convolution, and indicates the Fourier transform. ...

... Each ferrule will be used to plug approximately 300 holes. We must be sure the ferrules will not wear excessively during use; 1 mil reduction in diameter of a ferrule is enough to reduce light throughput by approximately 1%. ... Stainless steel ferrules offer lower precision (which will lose us approximately 1/2 to 1% light compared to ceramic), but they are relatively inexpensive, readily available with the hole diameter we require, and immune to cracking. ... Hence the wear was not very deep. ...

... Thanks to special permission from Cambridge University Press, we are able to bring you the complete Numerical Recipes in Fortran 77 book On-Line! ... 1.0 Introduction 1 . ... 2.4 Tridiagonal and Band Diagonal Systems of Equations 42 . ... 3.2 Rational Function Interpolation and Extrapolation 104 . ... 7.2 Transformation Method: Exponential and Normal Deviates 277 . ... 9.6 Newton-Raphson Method for Nonlinear Systems of Equations 372 . ... 12.3 FFT of Real Functions, Sine and Cosine Transforms 504 . ...

Next: Historical Notes Up: The Chirplet Transform: Previous: The Chirplet Transform: . ... One of these TF methods, the short-time Fourier transform (STFT), has been used extensively for analyzing speech, music, and other non-stationary signals. ... Another time-frequency representation (which might more appropriately be called a time-scale representation) is the well-known wavelet transformheil-walnut,mallat:theory,daubechies:transform,strangwavelets. ... Historical Notes . ...

Next: The continuous wavelet Up: The Wavelet Transform Previous: The Wavelet Transform . The Fourier transform is a tool widely used for many scientific purposes, but it is well suited only to the study of stationary signals where all frequencies have an infinite coherence time. ... Gabor [ 13 ] introduced a local Fourier analysis, taking into account a sliding window, leading to a time frequency-analysis. ... Tue Mar 28 16:52:29 MET DST 1995 ...

Tuesday 14:00-15:00 and 15:30-16:30 . Thursday 14:00-15:00 and 15:30-16:30 . ... Overview ( PDF ). ... Introduction ( PDF ). ... Photometric Systems ( PDF ). 3T. Tutorial ( PDF ). ... Optics Introduction ( PDF ). ... Telescope Optics ( PDF ). ... Instrument Optics ( PDF ). ... Imaging Systems ( PDF ). ... Slit Spectrographs ( PDF ). ... Integral-Field Spectrographs ( PDF ). ... Other Spectrographs ( PDF ). 11T. Tutorial ( PDF ). ... Detector systems ( PDF ). ... Adaptive optics ( PDF ). ...

Methods for calculating light scattering . by single particles . ... Exact methods . Separation of variables method . ... Point matching method . Integral equation method . Coupled dipoles method (Purcell-Pennypacker, CDM) . ... Approximate methods . ... Rayleigh-Debye-Gans approximation (RDG) . Generalizations of the RDG approximation . Anomalous diffraction approximation (AD) . ... Hybrid and simple analytical approximations . ... Created by V.I. Last modified: 12/08/03, V.I. ...

... We study in this paper the effect of shock excitation of leaky and surface modes by the p-polarized electromagnetic wave incident on the rapidly ionized gaseous or solid layer. ... For example, if [pic] (solid density, multiple ionized plasma), the basic frequency [pic], [pic], [pic] we find, that the wavelength of leaky wave [pic] is in soft x rays band. ... If [pic] (low density gaseous plasma), the basic frequency [pic], [pic], [pic] we find, that the wavelength of leaky wave [pic] is in THz band...

Subject of Astronomy. ... Celestial Sphere. ... Spherical Frames of Reference: Horisontal and Equatorial Coordinates, Ecliptical System. ... Transformation of Celestial Coordinates. ... Change of Object Coordinates as a Result of Diurnal Rotation of Celestial Sphere. Phenomenons, Which Lead to Celestial Coordinates Change. ... Motion of Equator, Ecliptic, and Their Poles. ... Diurnal Solar Motion on Different Latitudes. ... Time Equation. ... Apparent Motions and Configuration of Planets. ...

... The standard science quicklook processing produces over a dozen sky maps at each downlink, and these maps are automatically searched for potential transient point sources. ... We have found that a heuristic modification of a formula derived by Li & Ma (1983) provides reasonably accurate estimates of p -values for point source detections even for very low p -value detections. ... Case 1u. The most straightforward approach uses the signal , where . ... To get a p -value, use . ...

... The Armagh Observatory (see http://star.arm.ac.uk/) is the oldest scientific institution in Northern Ireland, founded by Archbishop Richard Robinson in 1790 as part of his dream to see the creation of a university in the City of Armagh. ... The Astropark, which is managed by the Observatory, includes two sundials and scale models of the solar system and the Universe, and features a number of outdoor exhibits and interpretation panels (see http://star.arm.ac.uk/astropark/). ... Armagh Planetarium . ...

... Astrophysics Group . ... COAST . Fringes and Power Spectra from COAST . ... After acquiring a star, measurements must be made of the (complex) fringe visibility on each baseline. ... Fortunately, even in the presence of very strong atmospheric turbulence there is a good observable: the phase of the triple product of the visibilities on three baselines, commonly known as the closure phase. ... We then form the power spectrum of the resultant data, and hence estimate the visibility. ...

... Introduction to Semiconductor Physics . ... Chemical bonds in semiconductors. ... Elements of band theory of semiconductors (perfect lattice). ... Elements of semiconductor band theory (semiconductors in external fields, imperfect crystals). ... Electron and hole energy spectra in constant electric field (quantum theory), shallow impurity levels. б Electron and hole statistics in semiconductors. ... Metal-semiconductor rectification. б Non-equilibrium electrons and holes in semiconductors. ...

... Sources of the quantum theory. ... Wave function and their physical interpretation. Schroedinger equation as a constraint on the physical state. Feynman's formulation of the quantum mechanics (path integration) and classical limit. Quantum mechanics postulates. States and observables, measurable physical values. ... State vector. ... Amplitude and crossection of scattering. ... M.: Nauka, 1974. ... Iroshnikov G.S. Path integral and coherent states in quantum mechanics and field theory. ...

Next: Characteristics of the Up: The Epsilon Aurigae Previous: The Epsilon Aurigae . ... Epsilon Aurig? is an F0 Ia star with an enigmatic companion which partially eclipses the visible star for 2 years every 27.1 years. ... The eclipse light curve has a long, flat minimum (Figure ), implying that the secondary is not appreciably convex. ... We develop hydrostatic models for the Aurig? secondary in Section D.3 and present synthetic eclipse light curves calculated using these models in Section D.4. ...

Next: Survey Methods Up: THE DEEP X-RAY RADIO Previous: THE DEEP X-RAY RADIO . Blazars are the most extreme variety of AGN known. ... The beaming hypothesis has been successful in reproducing the luminosity function of samples of blazars (e.g., Padovani & Urry 1990, 1991, 1992; Urry, Padovani & Stickel 1991), allowing the derivation of class properties such as the range of Lorentz factors and opening angles in the radio band (and also in other bands for BL Lacs). ...

... Binary orbits in the acceleration/period plane . Circular Orbits . ... We first present the equations for the period and acceleration of a pulsar in an eccentric binary system as a function of its position in the orbit. ... In Freire, Kramer & Lyne (2001) (from where most of this text and following equations are taken), we describe in more detail how circular binary orbits can be determined from the observed periods and accelerations of the pulsar. ... where is the orbital period of the binary. ...

... 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. ...

... This can be used to smooth the values in the column. Specifically, for input vector defined from to and convolver defined from to , colsmooth performs the following transformation: . ... These formulae automatically normalise the convolver . ... In fact use of a low-pass filter may be deceptive: the amount of noise may not have decreased very much although the graph looks much better because of the suppression of the more visible high-frequency end of the noise spectrum. ...