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Digitized Sky Survey
The Digitized Sky Survey (DSS) is a digitized version of several photographic astronomical surveys of the night sky, produced by the Space Telescope Science Institute between 1983 and 2006. Versions and source material The term Digitized Sky Survey originally referred to the publication in 1994 of a digital version of an all-sky photographic atlas used to produce the first version of the Guide Star Catalog. For the northern sky, the National Geographic Society – Palomar Observatory Sky Survey E-band (red, named after the Eastman Kodak IIIa-E emulsion used), provided almost all of the source data (plate code "XE" in the survey). For the southern sky, the J-band (blue, Eastman Kodak IIIa-J) of the ESO/ SERC Southern Sky Atlas (known as the SERC-J, code "S") and the "quick" V-band (blue or V in the Johnson–Kron–Cousins system, Eastman Kodak IIa-D) SERC-J Equatorial Extension (SERC-QV, code "XV"), from the UK Schmidt Telescope at the Australian Siding Spring Observatory, wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Data
Digital data, in information theory and information systems, is information represented as a string of discrete symbols each of which can take on one of only a finite number of values from some alphabet, such as letters or digits. An example is a text document, which consists of a string of alphanumeric characters . The most common form of digital data in modern information systems is ''binary data'', which is represented by a string of binary digits (bits) each of which can have one of two values, either 0 or 1. Digital data can be contrasted with ''analog data'', which is represented by a value from a continuous range of real numbers. Analog data is transmitted by an analog signal, which not only takes on continuous values, but can vary continuously with time, a continuous real-valued function of time. An example is the air pressure variation in a sound wave. The word ''digital'' comes from the same source as the words digit and ''digitus'' (the Latin word for ''finger'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Near Infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around 1 millimeter (300 GHz) to the nominal red edge of the visible spectrum, around 700 nanometers (430 THz). Longer IR wavelengths (30 μm-100 μm) are sometimes included as part of the terahertz radiation range. Almost all black-body radiation from objects near room temperature is at infrared wavelengths. As a form of electromagnetic radiation, IR propagates energy and momentum, exerts radiation pressure, and has properties corresponding to both those of a wave and of a particle, the photon. It was long known that fires emit invisible heat; in 1681 the pioneering experimenter Edme Mariotte showed that glass, though transparent to sunlight, obstructed radiant heat. In 1800 the astronomer Sir William Herschel discovered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Association Of Universities For Research In Astronomy
The Association of Universities for Research in Astronomy (AURA) is a consortium of universities and other institutions that operates astronomical observatories and telescopes. Founded October 10, 1957, with the encouragement of the National Science Foundation (NSF), AURA was incorporated by a group of seven U.S. universities: California, Chicago, Harvard, Indiana, Michigan, Ohio State, and Wisconsin. The first meeting of the Board of Directors took place in Ann Arbor, Michigan. Today, AURA has 47 member institutions in the United States and 3 international affiliate members. AURA began as a small organization dedicated to ground-based optical astronomy, managing a range of 1- to 4-meter telescopes and providing community advocacy for optical/infrared astronomy. Over the years, AURA expanded its focus to include Solar Astronomy and the Gemini 8-meter telescopes, going on to partner with other consortia such as WIYN (Wisconsin Indiana Yale & NOAO) and SOAR (Southern Astrophysi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CD-ROM
A CD-ROM (, compact disc read-only memory) is a type of read-only memory consisting of a pre-pressed optical compact disc that contains data. Computers can read—but not write or erase—CD-ROMs. Some CDs, called enhanced CDs, hold both computer data and audio with the latter capable of being played on a CD player, while data (such as software or digital video) is only usable on a computer (such as ISO 9660 format PC CD-ROMs). During the 1990s and early 2000s, CD-ROMs were popularly used to distribute software and data for computers and fifth generation video game consoles. DVD started to replace it in these roles starting in the early 2000s. History The earliest theoretical work on optical disc storage was done by independent researchers in the United States including David Paul Gregg (1958) and James Russel (1965–1975). In particular, Gregg's patents were used as the basis of the LaserDisc specification that was co-developed between MCA and Philips after MCA purchased ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photometry (astronomy)
Photometry, from Greek '' photo-'' ("light") and '' -metry'' ("measure"), is a technique used in astronomy that is concerned with measuring the flux or intensity of light radiated by astronomical objects. This light is measured through a telescope using a photometer, often made using electronic devices such as a CCD photometer or a photoelectric photometer that converts light into an electric current by the photoelectric effect. When calibrated against standard stars (or other light sources) of known intensity and colour, photometers can measure the brightness or apparent magnitude of celestial objects. The methods used to perform photometry depend on the wavelength region under study. At its most basic, photometry is conducted by gathering light and passing it through specialized photometric optical bandpass filters, and then capturing and recording the light energy with a photosensitive instrument. Standard sets of passbands (called a photometric system) are defined to allow a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gigabyte
The gigabyte () is a multiple of the unit byte for digital information. The prefix ''giga'' means 109 in the International System of Units (SI). Therefore, one gigabyte is one billion bytes. The unit symbol for the gigabyte is GB. This definition is used in all contexts of science (especially data science), engineering, business, and many areas of computing, including storage capacities of hard drives, solid state drives, and tapes, as well as data transmission speeds. However, the term is also used in some fields of computer science and information technology to denote (10243 or 230) bytes, particularly for sizes of RAM. Thus, prior to 1998, some usage of ''gigabyte'' has been ambiguous. To resolve this difficulty, IEC 80000-13 clarifies that a ''gigabyte'' (GB) is 109 bytes and specifies the term ''gibibyte'' (GiB) to denote 230 bytes. These differences are still readily seen for example, when a 400 GB drive's capacity is displayed by Microsoft Windows as 372 G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arcseconds
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The nautical mile (nmi) was originally defined as the arc length of a minute of latitude on a spherical Earth, so the actual Earth circumference is very near . A minute of arc is of a radian. A second of arc, arcsecond (arcsec), or arc second, denoted by the symbol , is of an arcminute, of a degree, of a turn, and (about ) of a radian. These units originated in Babylonian astronomy as sexagesimal subdivisions of the degree; they are used in fields that involve very small angles, such as astronomy, optometry, ophthalmology, optics, navigation, land surveying, and marksmanship. To express even smaller angles, standard SI prefixes can be employed; the milliarcsecond (mas) and microarcsecond (μas), for instance, are commonly used in astron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micrometre
The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Units (SI) equalling (SI standard prefix "micro-" = ); that is, one millionth of a metre (or one thousandth of a millimetre, , or about ). The nearest smaller common SI unit is the nanometre, equivalent to one thousandth of a micrometre, one millionth of a millimetre or one billionth of a metre (). The micrometre is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cells and bacteria, and for grading wool by the diameter of the fibres. The width of a single human hair ranges from approximately 20 to . The longest human chromosome, chromosome 1, is approximately in length. Examples Between 1 μm and 10 μm: * 1–10 μm – length of a typical bacterium * 3–8 μm – width of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pixel
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the smallest element that can be manipulated through software. Each pixel is a sample of an original image; more samples typically provide more accurate representations of the original. The intensity of each pixel is variable. In color imaging systems, a color is typically represented by three or four component intensities such as red, green, and blue, or cyan, magenta, yellow, and black. In some contexts (such as descriptions of camera sensors), ''pixel'' refers to a single scalar element of a multi-component representation (called a ''photosite'' in the camera sensor context, although ''sensel'' is sometimes used), while in yet other contexts (like MRI) it may refer to a set of component intensities for a spatial position. Etymology The w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microdensitometer
A microdensitometer is an optical instrument used to measure optical densities in the microscopic domain. J. C. Dainty and R. Shaw, ''Image Science'' (Academic, New york, 1974).T. H. James, ''The Theory of the Photographic Process'' (Eastman Kodak, Rochester, 1977). F. J. Duarte, ''Tunable Laser Optics'' (Elsevier Academic, New York, 2003) Chapter 10. A well-known microdensitometer, used in the photographic industry, is a granularity instrument or granularity machine. The granularity measurement involves the use of an optical aperture, 10-50 micrometers in diameter, and in the recording of thousands of optical density readings. The standard deviation of this series of measurements is known as the ''granularity'' of the measured transmission surface, optical film, or photographic film, in particular . An alternative version to the traditional point-by-point microdensitometer is the beam expanded laser microdensitometer.F. J. Duarte, Electro-optical interferometric microdensito ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perkin-Elmer
PerkinElmer, Inc., previously styled Perkin-Elmer, is an American global corporation focused in the business areas of diagnostics, life science research, food, environmental and industrial testing. Its capabilities include detection, imaging, informatics, and service. PerkinElmer produces analytical instruments, genetic testing and diagnostic tools, medical imaging components, software, instruments, and consumables for multiple end markets. PerkinElmer is part of the S&P 500 Index and operates in 190 countries. History Founding Richard Scott Perkin, Richard Perkin was attending the Pratt Institute in Brooklyn to study chemical engineering, but left after a year to try his hand on Wall Street. Still interested in the sciences, he gave public lectures on various topics. Charles Wesley Elmer, Charles Elmer ran a firm that supplied court reporters and was nearing retirement when he attended one of Perkin's lectures on astronomy being held at the Brooklyn Institute of Arts and Sci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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