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EULUMDAT is a data file format used for specification of photometric data especially intensity distributions from light sources such as lamps and luminaries. The file extension is .ldt. The format was proposed by Axel Stockmar (Light Consult Inc., Berlin) in 1990. The format is the European equivalent to the IES file format specified in IESNA ...
The photopic includes the CIE 1931 standard (solid), the Judd-Vos 1978 modified data (dashed), and the Sharpe, Stockman, Jagla & Jägle 2005 data (dotted). The horizontal axis is wavelength in nm. Photometry is a branch of optics that deals with measuring light in terms of its perceived brightness to the human eye. [1]
Quantity Unit Dimension [nb 1]Notes Name Symbol [nb 2] Name Symbol Luminous energy: Q v [nb 3]: lumen second: lm⋅s : T⋅J: The lumen second is sometimes called the talbot.: Luminous flux, luminous power
It includes positions, parallaxes, and proper motions for about 1.3 billion stars and positions of an additional 300 million stars, red and blue photometric data for about 1.1 billion stars and single colour photometry for an additional 400 million stars, and median radial velocities for about 7 million stars between magnitude 4 and 13.
An open file format is a file format for storing digital data, defined by a published specification usually maintained by a standards organization, and which can be used and implemented by anyone. For example, an open format can be implemented by both proprietary and free and open source software , using the typical software licenses used by each.
There are a number of organizations, from professional to amateur, that gather and share photometric data and make it available on-line. Some sites gather the data primarily as a resource for other researchers (ex. AAVSO) and some solicit contributions of data for their own research (ex. CBA): American Association of Variable Star Observers .
The format was created by Scott Ferguson and Daniel A. Chayes. [2] [3] The file format specifications and C source code for a library to read and write GSF files are available from Leidos, [1] who maintain both the format specification and the source code. [3] The GSF library source code is published under the GNU Lesser General Public License ...
1P21 photomultiplier tube. The UBV photometric system (from Ultraviolet, Blue, Visual), also called the Johnson system (or Johnson-Morgan system), is a photometric system usually employed for classifying stars according to their colors.