Astrophysics (Index)About

filter

(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 bands).

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.


(telescopes,equipment)
Further reading:
http://en.wikipedia.org/wiki/Astronomical_filter
http://astronomy.swin.edu.au/cosmos/F/Filters
https://mcdonaldobservatory.org/research/instruments/ubvri-filters
https://lovethenightsky.com/telescope-filters-explained/

Referenced by pages:
aperture photometry
Atlas 3D
B
bandwidth
BATC
color index
exoplanet eclipse light curve
first galaxies
H-alpha (Ha)
HEAO-2
Holmberg radius (RH)
I band
IPHAS
JHK photometric system (JHK)
K band
Lyman-break galaxy (LBG)
linearly variable filter (LVF)
particle spectrometer
passband
Palomar Four-filter Survey (PC)
photometric redshift (photo-z)
photometric system
photometry
rare designator prefixes
R band
sensitivity function (S)
sky subtraction
Sloan 2.5m Telescope
SkyMapper Southern Survey (SMSS)
spectral band
spectral flux density (S)
SPHEREx
Strömgren photometric system
synthetic photometry
U
UK Schmidt Survey
V
Voyager

Index