Imaging astronomical

The term data intensive applications or data intensive computing [1-3] is used to name a specific class of applications. Examples are web search providers, medical imaging, astronomical data analysis, weather simulation, or analyzing data collected during physical experiments. These problems all involve processing large amounts of data. The performance of such applications is usually limited by data access times rather than by pure computational power. 

Figure Bl.4.2. (A) Basic components of an astronomical heterodyne receiver. The photomicrograph in (B) presents the heart of a quasi-optical SIS mixer and its associated superconducting timing circuits, while the image in (C) shows the fiilly assembled mixer, as it would be incorporated into a low-temperature cryostat (J Zmuidzinas, private conmumication).

In the x-ray portion of the spectmm, scientific CCDs have been utilized as imaging spectrometers for astronomical mapping of the sun (45), galactic diffuse x-ray background (46), and other x-ray sources. Additionally, scientific CCDs designed for x-ray detection are also used in the fields of x-ray diffraction, materials analysis, medicine, and dentistry. CCD focal planes designed for infrared photon detection have also been demonstrated in InSb (47) and HgCdTe (48) but are not available commercially. 

The main consequence of isoplanatism is to reduce the sky coverage of AO systems. In addition, the PSF is not constant inside the field of view, a fact which complicates the analysis of images obtained using AO. For example, astronomical photometry is usually performed by comparing objects in the field to a known point spread function which is considered constant over the field. 

Nevertheless a number of blind deconvolution algorithms have been devised which are able to notably improve the quality of real (i.e. noisy) astronomical images (e.g. Ayers and Dainty, 1988 Lane, 1992 Thiebaut and Conan, 1995). 

Astronomical data is archived and released in the form of images (maps and outlines) and spectra (distribution of photons as a function of their energy). Duly classified, these constitute a huge database. The problem then is to give physical and astrophysical meaning to these cosmic archives, via an interpretation within the framework of the most relevant physical theory. 

The solitary astronomer with one eye permanently held against the eyepiece of his or her telescope is an image of the past. Today, we see with computer-regulated instruments, using the new techniques of active or adaptive optics. 

The key word in astronomy today is spectro-imaging. The combination of spectrum and image allows astronomers to deduce valuable information about objects under investigation, such as chemical composition, temperature, internal constitution and motion, or even the distance to the object. 

Cornwell, T.J. The Applications of Closure Phase to Astronomical Imaging, Science, 263 (July 21, 1989). 

With radio wave interferometric imaging of astronomical sources, it is typically assumed that the incoming radiation consists of planar waves. In this limit, any curvature of the incoming wavefronts is negligible. This far-field assumption is used for synthetic imaging and simplifies the imaging reconstruction process. However, most standoff THz applications do not fall in the far-field limit, and the simplified inverse Fourier transform of the electric field correlation - the far-field image reconstruction [99] - must be modified [100] to account for the curvature of the wavefronts in the near-field. 

Bob nods. It s the brightest star in the night sky. If we magnify the image you can see that it s actually a binary star, two stars with the brighter one 23 times as bright as our own Sun. Today I want to teach you about how earlier astronomers determined the distances from stars to Earth. ... 

Figure 8.1 Astronomers using NASA s Hubble Space Telescope have obtained images of the planetary nebula NGC 6751. Glowing in the constellation Aquila like a giant eye, the nebula is a cloud of gas ejected several thousand years ago from the hot star visible in its center. [Figure courtesy of NASA and The Hubble Heritage Team (STScI/AURA).]...

The images we see coming from modern telescopes encourage us to wonder about our place in this awesome Universe just as maps of the Earth used to lure us from our ordinary lives and towns to the farthest frontiers. Today s cosmic maps stimulate astronomers to explore and ponder the Universe in a manner similar to Marlowe in Joseph Conrad s Heart of Darkness ... 

Students for the Exploration and Development of Space, First direct image of the surface of a star, http //seds.Ipl.arizona.edu/nodes/NODEv5n4-3.html. Here s a nice quote about Betelgeuse Astronomers are drawn to objects that are big, nearby, and bright. That is why... 

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