Astrophysics (Index)About

U

(U band)
(photometric filter for ultraviolet light)

The letter U (or U band) is commonly used to indicate a passband located in the ultraviolet range (U for ultraviolet), typically for one located not far from the visible light range. The letter is also often used for a filter for the band (or more explicitly, a U filter), and to indicate a magnitude of a signal observed through such a filter, e.g., citing "U = 1.5". In the conventional UBV photometric system and its offshoots, the U band is centered around wavelength 365 nm, with a width of 66 nm (full width at half maximum). Other systems may have different specifications, in some cases, similar.


(EMR,ultraviolet,band,photometry)
Further reading:
https://en.wikipedia.org/wiki/Photometric_system
https://en.wikipedia.org/wiki/UBV_photometric_system
https://ui.adsabs.harvard.edu/abs/1953ApJ...117..313J/abstract
https://www.schoolsobservatory.org/learn/tech/instruments/filters
https://sites.astro.caltech.edu/~george/ay122/Bessel2005ARAA43p293.pdf
WaveLFreqPhoton
Energy
  
365nm821THz3.4eVU

Referenced by pages:
color index
color-color diagram (CCD)
passband
SkyMapper Southern Survey (SMSS)
Strömgren photometric system
UBV photometric system
UVJ diagram
Vega

Index