(studying starlight through bandpass filters)
In astronomy, the term photometry is used for
the study of the brightness (magnitude) of stars and other bodies,
optionally using bandpass filters to
measure magnitudes over specific spectral ranges,
e.g., to determine color indices. The results of such
observation may be called the star's photometry.
This is as opposed to a more complete characterization
of the body's light via spectroscopy, which requires
a more specialized instrument. Photometry has the advantage
of requiring less light (apparent magnitude), thus
can be done at a greater distance and can be used with many more
stars. It also is naturally "multi-object", also making
it much more efficient to survey many stars.
The passbands used have been standardized (photometric systems)
to allow comparison and general use of photometric data.
Filters with different passband widths are used, according to
need and light-availability, yielding some levels of spectral
detail, but short of using full spectroscopy. For example,
direct imaging of extra-solar planets offers limited light,
making photometry more practical than spectroscopy.
Some subtypes of photometry:
- broad band photometry - passband width on the order of 100 nm.
- intermediate band photometry - on the order of 20 nm.
- narrow band photometry - on the order of 5 nm.
- spectral photometry - for even narrower passbands.
- precision photometry - (or high-precision or ultra-precision, etc.) producing reliable magnitude measurements in higher precision than typical, e.g., thousandths.
All Sky Automated Survey (ASAS)
All-Sky Compiled Catalogue (ASCC)
Catalog of Azzopardi & Vigneau (AzV)
Balmer-break galaxy (BBG)
California-Kepler Survey (CKS)
Carlsberg Meridian Catalogue (CMC)
Carnegie Supernova Project (CSP)
Cerro Tololo Inter-American Observatory (CTIO)
Dark Energy Survey (DES)
Deep Lens Survey (DLS)
exoplanet eclipse light curve
ESO Nearby Abell Cluster Survey (ENACS)
extremely red object (ERO)
Extreme Ultraviolet Explorer (EUVE)
Hawaii K-band Galaxy Survey
Herschel Space Observatory
Bright Star Catalog (HR)
JHK photometric system (JHK)
Large Synoptic Survey Telescope (LSST)
Magellanic Clouds Photometric Survey (MCPS)
NOAO Deep Wide-field Survey (NDWFS)
photometric redshift (photo-z)
Qatar Exoplanet Survey (QES)
Supernova Cosmology Project (SCP)
Sloan Digital Sky Survey (SDSS)
SkyMapper Southern Survey (SMSS)
Swope Supernova Survey (SSS)
stellar parameter determination
stellar temperature determination
Strömgren photometric system
Type Ia supernova
UBV photometric system
VLT Survey Telescope (VST)
Wide Field Infrared Explorer (WIRE)