angular resolution
(spatial resolution, resolution)
(measure of a telescope's ability to distinguish spatial detail)
Angular resolution is a measure of the ability of
a telescope (optical, radio, etc.)
to distinguish spatial detail. "Angular" refers to the measure
describing an angle between two distinguishable features of an image
with the observer as the vertex of the angle.
The physics of diffraction determines a minimum angular
resolution of a (circular cross-section) telescope
based upon the size of its aperture.
A telescope's image of a single point of light in the sky consists not of
a dot, but is spread/smeared into a specific pattern:
a disk surrounded by rings of
light (known as an Airy disk).
If the angle between two such points is sufficiently
small, their two disks are not distinct from each other.
Lord Rayleigh's Rayleigh criterion quantifies a telescope's
resolution as the angular distance between two points in
the celestial sphere such that within the image, one point's
disk's maximum brightness (at the center) coincides with the other
point's disk's minimum brightness between the center spot and
the first ring surrounding it.
The following formula calculates this angle:
λ
θ = 1.220 ———
D
θ is the angular
resolution (radians),
λ is the wavelength,
and D is the aperture diameter
(using the same distance-unit for the wavelength and aperture, e.g., meters).
Another criterion, the Dawes limit aka Dawes criterion,
is essentially the same criterion, but specific to optical telescopes,
based on a representative wavelength within the optical range
(about 460 nm, which is blue):
R = 4.56/D
R is arcseconds and D is in inches (116 is a reasonably-equivalent constant
for D in millimeters: 4.56 inches equals 115.824 mm).
With multiple telescopes arranged as
an interferometer, smaller angular resolution
can be obtained. Also, computer-based analysis
on the overlapping Airy disks can sometimes identify
and locate individual sources, achieving higher angular
resolution than the Rayleigh criterion would imply.
The term speckle suppression includes this and other
methods of surpassing the Rayleigh criterion.
Example angular resolutions (based on Rayleigh criterion):
Interferometry:
Spektr-R's 10-meter dish limited it to bright radio sources.
(telescopes,optics,measure,specification)
Further reading:
https://en.wikipedia.org/wiki/Angular_resolution
https://en.wikipedia.org/wiki/Dawes%27_limit
https://astronomy.swin.edu.au/cosmos/R/Resolution
https://dictionary.obspm.fr/index.php?showAll=1&formSearchTextfield=angular+resolution
https://astronomy.swin.edu.au/cosmos/r/rayleigh+criterion
http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/Raylei.html
https://jila.colorado.edu/~ajsh/courses/astr1120_03/text/chapter2/L2S4.htm
https://www.astro.umd.edu/~thuard/astr288c/lecture6-notes.pdf
https://www.telescope-optics.net/telescope_resolution.htm
http://labman.phys.utk.edu/phys136core/modules/m9/resolving_power.html
https://coolwiki.ipac.caltech.edu/index.php/Resolution_Overview
Referenced by pages:
Airy disk
angular magnification
aperture
aperture masking interferometry (AMI)
aperture synthesis
apodization
Archeops
ASCA
ASTHROS
astrometry
Atacama Cosmology Telescope (ACT)
Atacama Large Millimeter Array (ALMA)
ATHENA
Australia Telescope Compact Array (ATCA)
AXIS
baseline
beam
blind survey
C-BASS
Caltech Submillimeter Observatory (CSO)
CARMA EDGE
CHARA
chromatic aberration
collecting area
Colossus Telescope
Compton telescope
CONCERTO
confusion limit
correlator
Cosmic Dawn Intensity Mapper (CDIM)
COSMOSOMAS
counterpart
CRATES
detective quantum efficiency (DQE)
diffraction
diffraction limited
DSHARP
EMPIRE Survey
EPOXI
etendue (AΩ)
Event Horizon Telescope (EHT)
extended source
field of view (FOV)
Fourth Cambridge Catalog of Radio Sources (4C)
Galactic All-sky Survey (GASS)
GLEAM
Hale Telescope
HARMONI
HEAO-2
High Resolution Fly's Eye (HiRes)
high-resolution imaging
imaging spectrometer
integral field spectrograph
integral field unit (IFU)
interferometry
Large Altazimuth Telescope (BTA-6)
Large Millimeter Telescope (LMT)
lucky imaging
Lucy
Lynx
Mars Express
Mars Reconnaissance Orbiter (MRO)
millimeter astronomy
Mount Wilson Observatory (MWO)
optical interferometer
parallax
PAWS
PHANGS
PHIBSS
plate scale
point source
PSF fitting
radio astronomy
RATAN-600
RELIKT-1
ROSAT
SCUBA
seeing
Sloan Digital Sky Survey (SDSS)
SOAR Telescope (SOAR)
solar telescope
speckle imaging
speckle masking
speckle suppression
spectral resolution
Spektr-R
SPHEREx
stellar distance determination
Subaru Telescope
submillimeter astronomy
SuperBIT
surface brightness fluctuation (SBF)
SUSI
synthetic aperture radar (SAR)
Tianwen-1 (TW-1)
Uhuru
VERA
Very Large Array (VLA)
Very Long Baseline Array (VLBA)
very-long-baseline interferometry (VLBI)
VLASS
WIYN 3.5m Telescope
Index