scholarly journals Estimation of normalized point-source sensitivity of segment surface specifications for extremely large telescopes

2013 ◽  
Vol 52 (18) ◽  
pp. 4111 ◽  
Author(s):  
Byoung-Joon Seo ◽  
Carl Nissly ◽  
Mitchell Troy ◽  
George Angeli ◽  
Robert Bernier ◽  
...  
Keyword(s):  
Point Source ◽  
Large Telescopes

scholarly journals On the Importance of Active Image Stabilisation

1984 ◽  
Vol 79 ◽  
pp. 367-378
Author(s):  
J.E. Noordam
Keyword(s):  
Point Source ◽  
Speckle Interferometry ◽  
Aperture Synthesis ◽  
Atmospheric Conditions ◽  
Optical Telescope ◽  
Aperture Diameter ◽  
Logical Approach ◽  
Optical Aperture ◽  
Large Telescopes ◽  
Mirror Telescope

AbstractThe performance of an optical telescope can be improved considerably by opening the shutter only at moments of good seeing. The resulting instantaneous highresolution images must be corrected for shift before adding them all together. The optimum aperture diameter for which this technique works well is 1 meter or less, depending on atmospheric conditions. Image stabilisation not only improves the resolution and thus the point-source sensitivity, but it is also expected to improve the performance of speckle interferometry and optical aperture synthesis. This makes its implementation on large telescopes desirable. While it is certainly possible to do this by treating a large filled aperture like a set of independent subapertures, a much more logical approach would be to build an array of 1-meter telescopes, preferably mounted in a single large frame so that it can be pointed in all directions without extensive pathlength compensation. Such a “Many Mirror Telescope” has many advantages, and is feasible because image stabilisation helps to solve the beam-combining problem.

scholarly journals Measuring the Linearity of Radio?Astronomy Receivers

1962 ◽  
Vol 15 (4) ◽  
pp. 572
Author(s):  
MM Komesaroff ◽  
DS Mathewson
Keyword(s):  
Point Source ◽  
Flux Density ◽  
Radio Astronomy ◽  
Noise Temperature ◽  
Low Noise ◽  
Receiver Noise ◽  
Large Telescopes

A convenient practice which is frequently adopted in observational radio 'astronomy is to express all aerial temperatures in terms of the temperature produced by a " point source" of known flux density. A difficulty with this procedure is that, with large telescopes and modern low-noise receivers, the aerial temperatures due to any of the better-known discrete sources are usually comparable with or greater than the receiver noise temperature.

scholarly journals Analysis of normalized point source sensitivity as a performance metric for large telescopes

2009 ◽  
Vol 48 (31) ◽  
pp. 5997 ◽  
Author(s):  
Byoung-Joon Seo ◽  
Carl Nissly ◽  
George Angeli ◽  
Brent Ellerbroek ◽  
Jerry Nelson ◽  
...  
Keyword(s):  
Point Source ◽  
Performance Metric ◽  
Large Telescopes ◽  
A Performance

XRMF applications of a monolithic, polycapillary, focusing x-ray optic

1996 ◽  
Vol 54 ◽  
pp. 240-241
Author(s):  
D. A. Carpenter ◽  
Ning Gao ◽  
G. J. Havrilla
Keyword(s):  
Trace Elements ◽  
Point Source ◽  
Focal Spot ◽  
Fluorescence Analysis ◽  
X Rays ◽  
Focal Distance ◽  
Spot Diameter ◽  
X Ray ◽  
Focal Spot Diameter

A monolithic, polycapillary, x-ray optic was adapted to a laboratory-based x-ray microprobe to evaluate the potential of the optic for x-ray micro fluorescence analysis. The polycapillary was capable of collecting x-rays over a 6 degree angle from a point source and focusing them to a spot approximately 40 µm diameter. The high intensities expected from this capillary should be useful for determining and mapping minor to trace elements in materials. Fig. 1 shows a sketch of the capillary with important dimensions.The microprobe had previously been used with straight and with tapered monocapillaries. Alignment of the monocapillaries with the focal spot was accomplished by electromagnetically scanning the focal spot over the beveled anode. With the polycapillary it was also necessary to manually adjust the distance between the focal spot and the polycapillary.The focal distance and focal spot diameter of the polycapillary were determined from a series of edge scans.

The First Galaxies in the Universe

2013 ◽  
Author(s):  
Abraham Loeb ◽  
Steven R. Furlanetto
Keyword(s):  
Galaxy Evolution ◽  
Big Bang ◽  
First Stars ◽  
Distant Galaxies ◽  
Formation And Evolution ◽  
Early Galaxies ◽  
First Galaxies ◽  
Large Telescopes ◽  
New Generation ◽  
The Big Bang

This book provides a comprehensive, self-contained introduction to one of the most exciting frontiers in astrophysics today: the quest to understand how the oldest and most distant galaxies in our universe first formed. Until now, most research on this question has been theoretical, but the next few years will bring about a new generation of large telescopes that promise to supply a flood of data about the infant universe during its first billion years after the big bang. This book bridges the gap between theory and observation. It is an invaluable reference for students and researchers on early galaxies. The book starts from basic physical principles before moving on to more advanced material. Topics include the gravitational growth of structure, the intergalactic medium, the formation and evolution of the first stars and black holes, feedback and galaxy evolution, reionization, 21-cm cosmology, and more.

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