(passband filter, bandpass filter)
(optical device to filter out part of the EMR spectrum)
In astronomy, optical filters are used
with telescopes to limit the spectrum reaching a sensor,
by which an image over a more-limited range of electromagnetic radiation can be produced.
A sharp cutoff at some precise wavelength
is typically unachievable, so their sensitivity function
generally shows a hill-like (or somewhat bell-curve-like) peak.
They are used for visible light and adjacent regions of
the EMR spectrum (within the infrared and ultraviolet
The term passband can be thought of as the specification
of such a filter, but the two terms are often treated almost as synonyms,
and often the letter identifying the band is used to refer
to the filter or to the intensity of an object (star)
seen through the filter. The definition and standardization of
passbands similarly applies to filters for those passbands.
There are also filters for higher energy EMR, e.g., X-rays.
Referenced by pages:
exoplanet eclipse light curve
Holmberg radius (RH)
JHK photometric system (JHK)
Lyman-break galaxy (LBG)
linearly variable filter (LVF)
Palomar Four-filter Survey (PC)
photometric redshift (photo-z)
rare designator prefixes
sensitivity function (S)
Sloan 2.5m Telescope
SkyMapper Southern Survey (SMSS)
spectral flux density (S)
Strömgren photometric system
UK Schmidt Survey