نتایج جستجو برای: astronomical technique

تعداد نتایج: 618591  

2012
DAVID C. WEBER

A DIRECTOR OF A UNIVERSITY LffiRARY has many problems. Besides financial problems, he must decide how to build collections, what resources in the collections can best serve faculty and students, what kind of bibliographical control must be provided, how to cope with the growth of collections and building problems that ensue, how to make more effective public services, how to provide instruction...

2016
Louis Marmet

This paper gives a compilation of physical mechanisms producing red-shifts of astronomical objects. Over sixty proposed mechanisms are listed here for the purpose of quantitative comparisons. These mechanisms may not individually account for all observations but are adapted to particular situations such as the solar limb redshift, the red-shift of quasars or the cosmological red-shift. However,...

Journal: :Int. J. Imaging Systems and Technology 1995
Fionn Murtagh Jean-Luc Starck Albert Bijaoui

Multiresolution transforms, including a wavelet transform, are applied to image visualization, image restoration, filtering and compression, and object detection. Variance stabilization is used, when appropriate, to cater for common astronomical image noise models. We discuss validation of such methods in the case of astronomical image processing. A range of examples illustrate the effectivenes...

1999

Virtually all of our knowledge of astronomical objects was gained by observation of their light. We know how to make many kinds of detailed measurements on light, among them brightness, spectrum, polarization state, degree of coherence, and the shape of light-emitting regions. We also know a great deal about the mechanisms by which light can be produced in nature, and we can thus use any accura...

2017
Xiaopeng Li Wenyuan Xu Song Wang Xianshan Qu

Photos have been commonly used in our society to convey information, and the associated contextual information (i.e., the capture time and location) is a key part of what a photo conveys. However, the contextual information can be easily tampered or falsely claimed by forgers to achieve malicious goals, e.g., creating fear among the general public or distorting public opinions. Thus, this paper...

2001
Michael Rebstock

Application functionality in business-to-business marketplaces today covers a smaller range of a company's overall procurement activities. Not every product or service can be acquired using catalogs, auctions or tenders. With the growing number of market transactions to be supported electronically, we expect a range of applications that will handle other forms of transactions. We hold that to a...

1999
Fabien Malbet Pierre Kern Isabelle Schanen-Duport Jean-Philippe Berger Karine Rousselet Pierre Benech

We propose a new instrumental concept for long-baseline optical single-mode interferometry using integrated optics which were developed for telecommunication. Visible and infrared multi-aperture interferometry requires many optical functions (spatial filtering, beam combination, photometric calibration, polarization control) to detect astronomical signals at very high angular resolution. Since ...

2004
Geoffrey C. Bower

Radio frequency interference (RFI) is a significant problem for current and future radio telescopes. We describe here a method for post-correlation cancellation of RFI for the special case of an extended source observed with an interferometer that spatially resolves the astronomical signal. In this circumstance, the astronomical signal is detected through the auto-correlations of each antenna b...

2008
N Capitaine B Guinot

The IAU-1976 System of astronomical constants includes three astronomical units (i.e. for time, mass and length). This paper reports on the status of the astronomical unit of length (ua) and mass (MSun) within the context of the recent IAU Resolutions on reference systems and the use of modern observations in the solar system. We especially look at a possible re-definition of the ua as an astro...

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