Astrophysics (Index)About

spectral resolution

(resolution)
(measure of a spectrograph's ability to resolve features of the spectrum)

Spectral resolution is a measure of a spectrograph's ability to distinguish features in the spectrum, typically noted as Δλ, meaning the smallest division in wavelengths that the spectrograph can distinguish, i.e., a distance, e.g., in nm. The (spectral) resolving power (R) is defined as:

    λ
R = ——
    Δλ

(Note that what is termed resolving power is very often labeled as the spectral resolution.) Examples:

There is a tradeoff between spectral resolution and throughput, i.e., how much light is necessary to produce the spectrum date, which is (apparent) brightness of the source times the time necessary to produce the spectral energy distribution (SED). For example, for extremely distant galaxies that are dim to us, spectrography may be impossible, and approaching such distances, higher-resolution SEDs may be impractical or impossible.

Radial velocity (RV) measurements using spectral lines depend upon spectral resolution, but far more precise RVs are now inferred than that implied by spectral resolution of the spectrograph: astrophysicists and engineers constantly develop the techniques contributing to such precise RVs, but a basic technique is to analyze the SEDs for a number of lines and/or from a number of observations and statistically work out the most likely RV-pattern to produce all of them, presuming the relatively-rough measured wavelengths of the spectral line are probabilistically scattered according to an appropriate probability density function, e.g., the normal distribution.


The term resolving power can also logically refer to that of angular resolution and is occasionally used as such.


(instruments,measure,EMR,specification,spectrography)
Further reading:
https://en.wikipedia.org/wiki/Spectral_resolution
https://dictionary.obspm.fr/index.php?formSearchTextfield=spectral+resolution&showAll=1
http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/gratres.html
http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/instruments/phy217_inst_dispersion.html
https://www.ossila.com/en-us/pages/spectrometer-resolution

Referenced by pages:
Anglo-Australian Telescope (AAT)
ARGOS
ASCA
BigBOSS
Chandra X-ray Observatory (CXO)
CONCERTO
continuous absorption
Cosmic Dawn Intensity Mapper (CDIM)
CRIRES
cross dispersion spectrograph
double-line spectroscopic binary (SB2)
EnVision
European Extremely Large Telescope (E-ELT)
European Southern Observatory Very Large Telescope (ESO VLT)
EXCLAIM
EXPRES
filter bank
fine structure
Fraunhofer lines
Gemini Observatory
Gran Telescopio Canarias (GTC)
ground state
H-alpha (Ha)
H3 Survey (H3)
HARMONI
HARPS
HCI
HERMES
Hobby-Eberly Telescope (HET)
HRS
Hubble Space Telescope (HST)
immersion grating
Interstellar Medium Absorption Profile Spectrograph (IMAPS)
IRAS
IRTF
James Webb Space Telescope (JWST)
Keck Observatory
Large Binocular Telescope (LBT)
Las Cumbres Observatory (LCO)
line blanketing
Lyman-alpha forest
Lynx
Magellan Telescopes
Mercator Telescope
MICADO
Milky Way Mapper (MWM)
Multi-object Optical and Near-IR Spectrograph (MOONS)
New Technology Telescope (NTT)
NEWS
NIRPS
NIRSpec
OSO 8
PESSTO
PRIMA
radial velocity method
Southern African Large Telescope (SALT)
spectral band
spectral line designation
spectroscopy
SPHEREx
SPICA
Telescopio Nazionale Galileo (TNG)
TripleSpec (TSpec)
Tubingen Ultraviolet Echelle Spectrometer (TUES)
Upper Atmosphere Research Satellite (UARS)
Víctor M. Blanco Telescope
WEAVE
Wien's displacement law
William Herschel Telescope (WHT)
WINERED
Zeeman effect

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