- Photometric system
In
astronomy , a Photometric system is a set of well-defined passbands (of filters), with a known sensitivity to incident radiation. The sensitivity usually depends on the optical system, detectors and filters used. For each photometric system a set of primary standard stars is provided.The first known standardized photometric system is the Johnson-Morgan or
UBV photometric system (1953). At present, there are more than 200 photometric systems.Photometric systems are usually characterized according to the widths of their passbands:
* broadband (passbands wider than 30 nm (the most widely used is Johnson-MorganUBV system )),
* intermediate band (passbands widths between 10 and 30 nm),
* narrow band (passbands widths less than 10 nm).Photometric Letters
The letters designate a region of a wavelength of light. Majority of the letters span from near-
ultraviolet (NUV) to visible and majority of the near-infrared (NIR).Note,
indigo andcyan are not standard colors [ [http://hyperphysics.phy-astr.gsu.edu/Hbase/vision/specol.html Spectral Colors] ] . Orange, yellow, and green fall under visual bands, while violet and purple are under the blue bands.Note, the letters are not standards, they are just recognized byAstrophysicists .Used Filters
The filters currently being used by other telescopes or organizations [ [http://www.astronomy2006.com/files/glass_talk.pdf Classic and New Photometric Systems] , IAU, Prague 2006] .
Units of measurements:
* Å =Ångström
* nm =nanometer
* μm = micronReferences
# Johnson, H. L.; Morgan, W. W. (1953), "Fundamental stellar photometry for standards of spectral type on the revised system of the Yerkes spectral atlas", The Astrophysical Journal, vol. 117, pp. 313-352 [http://adsabs.harvard.edu/abs/1953ApJ...117..313J]
# [http://ulisse.pd.astro.it/Astro/ADPS/Systems/index.html The Asiago Database on Photometric Systems]
# Michael S. Bessell (2005), "STANDARD PHOTOMETRIC SYSTEMS", Annual Reviews of Astronomy and Astrophysics vol. 43, pp. 293–336
# [http://adsabs.harvard.edu/abs/2005A&A...434..987A Infrared portrait of the nearby massive star-forming region IRAS 09002-4732] , Apai, D.; Linz, H.; Henning, Th.; Stecklum, B., 2005ee also
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