An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 5 Search : digital
analog-to-digital converter
  هاگردگر ِ آناگویه-رقمی   
hâgardgar-e ânâguyé-raqami

Fr.: convertisseur analogique-numérique   

In electronics, a device that converts the analog signal to → analog-to-digital units or counts.

analogue; → digital; → converter.

analog-to-digital unit (ADU)
  یکای ِ آناگویه-رقمی   
yekâ-ye ânâguyé-raqami

Fr.: unité analogue-numérique   

A number that represents a → charge-coupled device (CCD)'s output and is proportional to the → electron charge created by the → photons, plus the constant → bias offset. The relationship between the ADUs generated and the number of electrons acquired on the CCD is defined by the → CCD gain. Intensities given in ADUs provide a convenient method for comparing images and data generated by different cameras. Also referred to as → count and digital number. In most cases, the analog signal is digitalized by an analog-to-digital (A/D) converter and fed into a computer where further manipulation and analysis are done on what the detector originally produced from the star's photons (Howell, S.B., Handbook of CCD Astronomy, Cambridge Univ. Press, 2000).

analogue; → digital; → unit.

digital
  رقمی   
raqami (#)

Fr.: numérique   

1) Of or pertaining to a digit.
2) Representing data as a series of numerical values. Often opposed to → analogue.

digit + → -al.

digital computer
  رایانگر ِ رقمی   
râyângar-e raqami (#)

Fr.: ordinateur numérique   

A computer that accepts and operates with → discrete data in the form of combinations of digits, letters, or other characters. In modern terminology, generally called computer.

digital + → computer.

Sloan Digital Sky Survey (SDSS)
  بردید ِ عددی ِ آسمان ِ Sloan   
bardid-e adadi-ye âsmân-e Sloan

Fr.: relevé numérique du ciel Sloan   

A major → redshift survey using a dedicated 2.5-m wide angle telescope with different modes in → imaging and → spectroscopy. The telescope, a modified → Ritchey-Chretienaltitude-azimuth type is located at Apache Point Observatory, south east New Mexico, United States. A large consortium of universities and institutions all over the world participate in the project. The telescope started its observations in 2000, taking spectra and images of about 35% of the night sky, with 3 million spectra and 500 million images coming together to form the most comprehensive astrophysical catalog in the world. This catalog contains millions of galaxies up to z = 1, bright → quasars up to z = 6, with images in five major filter bands (u, g, r, i and z). SDSS was divided into multiple surveys/projects: SDSS I (2000-2005); SDSS II (2005-2008), including the Sloan Supernova Survey; SDSS III (2008-2014), including the APO Galactic Evolution Experiment (APOGEE), Baryon Oscillation Spectroscopic Survey (BOSS); SDSS IV (2014-2020), including the Mapping Nearby Galaxies at APO (MaNGA).

Named after the Alfred P. Sloan Foundation, which contributed significant funding; → digital; → sky; → survey.