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Photometric system

Set of well-defined passbands (or filters), with a known sensitivity to incident radiation

Summary

Set of well-defined passbands (or filters), with a known sensitivity to incident radiation

In astronomy, a photometric system is a set of well-defined passbands (or optical filters), with a known sensitivity to incident radiation. The sensitivity usually depends on the optical system, detectors and filters used. For each photometric system a set of primary standard stars is provided.

A commonly adopted standardized photometric system is the Johnson-Morgan or UBV photometric system (1953). At present, there are more than 200 photometric systems.

Photometric systems are usually characterized according to the widths of their passbands:

broadband (passbands wider than 30 nm, of which the most widely used is Johnson-Morgan UBV system)
intermediate band (passbands between 10 and 30 nm wide)
narrow band (passbands less than 10 nm wide)

Photometric letters

Each letter designates a section of light of the electromagnetic spectrum; these cover well the consecutive major groups, near-ultraviolet (NUV), visible light (centered on the V band), near-infrared (NIR) and part of mid-infrared (MIR). The letters are not standards, but are recognized by common agreement among astronomers and astrophysicists.

The use of U,B,V,R,I bands dates from the 1950s, being single-letter abbreviations.

With the advent of infrared detectors in the next decade, the J to N bands were labelled following on from near-infrared's closest-to-red band, I.

Later the H band was inserted, then Z in the 1990s and finally Y, without changing earlier definitions. Hence, H is out of alphabetical order from its neighbours, while Z,Y are reversed from the alphabetical – higher-wavelength – sub-series which dominates current photometric bands.

Filter
Letter	Binney, J.]]; Merrifield M. Galactic Astronomy, Princeton University Press, 1998, ch. 2.3.2, pp. 53	The width of the band of the curve's 50% upper values (that is, peak) for a natural curve of paradigm source of this light}} (archetypal Bandwidth) (Δλ)	Variant(s)	Description
Ultraviolet
U	365 nm	66 nm	u, u', u*	"U" stands for ultraviolet.
Visible
B	445 nm	94 nm	b	445}}; color:#ffffff; text-align:center;"	"B" stands for blue.
last1=Bessell	first1=Michael S.	title=Standard Photometric Systems	journal=Annual Review of Astronomy and Astrophysics	volume=43	issue=1	date=September 2005	pages=293–336	issn=0066-4146	doi=10.1146/annurev.astro.41.082801.100251	bibcode=2005ARA&A..43..293B	url=http://www.mso.anu.edu.au/~bessell/araapaper.pdf}}	464 nm	128 nm	g, g'	464}}; color:#ffffff; text-align:center;"	"G" stands for green.
V	551 nm	88 nm	v, v'	551}}; color:#000000; text-align:center;"	"V" stands for visual.
R	658 nm	138 nm	r, r', R', Rc, Re, Rj	658}};" align="center" style="color:#ffffff;"	"R" stands for red.
Near-Infrared
I	806 nm	149 nm	i, i', Ic, Ie, Ij	"I" stands for infrared.
Z	900 nm	152 nm	z, z'
Y	1020 nm	120 nm	y
J	1220 nm	213 nm	J', Js
H	1630 nm	307 nm
K	2190 nm	390 nm	K Continuum, K', Ks, Klong, K8, nbK
L	3450 nm	472 nm	L', nbL'
Mid-Infrared
M	4750 nm	460 nm	M', nbM
N	10500 nm	2500 nm
Q	21000 nm	5800 nm	Q'

Note: colors are only approximate and based on wavelength to sRGB representation (when possible).

Combinations of these letters are frequently used; for example the combination JHK has been used more or less as a synonym of "near-infrared", and appears in the title of many papers.

Filters used

The filters currently being used by other telescopes or organizations.

Units of measurements:

Å = Ångström
nm = nanometre
μm = micrometre

Name	Filters	Link
2.2 m telescope at La Silla, ESO	J = 1.24 μm	H = 1.63 μm
2MASS/PAIRITEL	J = 1.25 μm	H = 1.65 μm
CFHTLS (Megacam)	u* = 374 nm	g' = 487 nm
Chandra X-ray Observatory	LETG = 0.08-0.2 keV	HETG = 0.4-10 keV
CTIO	J = 1.20 μm	H = 1.60 μm
Cousins RI photometry	Rc = 647 nm	Ic = 786.5 nm
the Dark Energy Camera	g = 472.0 nm	r = 641.5 nm
DENIS	I = 0.79 μm	J = 1.24 μm
Eggen RI photometry	Re = 635 nm	Ie = 790 nm
FIS	N60 = 65.00 μm	WIDE-S = 90.00 μm
Gaia	G = 673 nm	GBP = 532 nm
GALEX	NUV = 175–280 nm	FUV = 135–175 nm
GOODS (Hubble ACS)	B = 435 nm	V = 606 nm
HAWC+	Band 1 = 53 μm	Band 2 = 89 μm
HDF	300 nm	450 nm
IRTF NSFCAM	J = 1.26 μm	H = 1.62 μm
ISAAC UTI/VLT	Js = 1.2 μm	H = 1.6 μm
Johnson system (UBV)	U = 364 nm	B = 442 nm
Vera C. Rubin Observatory (LSST)	u = 320.5–393.5 nm	g = 401.5–551.9 nm
OMC	Johnson V-filter = 500-580 nm
Pan-STARRS	g = 481 nm	r = 617 nm
ProNaOS/SPM	Band 1 = 180-240 μm	Band 2 = 240-340 μm
Sloan, SDSS	u' = 354 nm	g' = 475 nm
SPIRIT III	Band B1 = 4.29 μm	Band B2 = 4.35 μm
Spitzer IRAC	ch1 = 3.6 μm	ch2 = 4.5 μm
Spitzer MIPS	24 μm	70 μm
Stromvil filters	U = 345 nm	P = 374 nm
Strömgren filters	u = 350 nm	v = 411 nm
UKIDSS (WFCAM)	Z = 882 nm	Y = 1031 nm
Vilnius photometric system	U = 345 nm	P = 374 nm
VISTA IRC	Z = 0.88 μm	Y = 1.02 μm
WISE	W1 = 3.4 μm	W2 = 4.6 μm
XMM-Newton OM	UVW2 = 212 nm	UVM2 = 231 nm
XEST Survey	UVW2 = 212 nm	UVM2 = 231 nm

Note: colors are only approximate and based on wavelength to sRGB representation (when possible).

References and footnotes

References

(2005). "Standard Photometric Systems". Annual Review of Astronomy and Astrophysics.
[http://hyperphysics.phy-astr.gsu.edu/Hbase/vision/specol.html Spectral Colors]
[[James Binney. Binney, J.]]; Merrifield M. ''Galactic Astronomy'', Princeton University Press, 1998, ch. 2.3.2, pp. 53
(September 2005). "Standard Photometric Systems". Annual Review of Astronomy and Astrophysics.
(23 May 2005). "JASMINE: Japan Astrometry Satellite Mission for INfrared Exploration". Proceedings of the International Astronomical Union.
[http://www.cnofs.org/Handbook_of_Geophysics_1985/] Handbook of Geophysics and the Space Environment 1985, Air Force Geophysics Laboratory, 1985, ed. Adolph S. Jursa, Ch. 25, Table 25-1
"Light wavelength to RGB Converter".
(2011). "Near-Infrared (Jhk) Photometry of 131 Northern Galactic Classical Cepheids". The Astrophysical Journal Supplement Series.
[http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1990MNRAS.247..624A&db_key=AST&nosetcookie=1 A study of the Chamaeleon I dark cloud and T-association. II – High-resolution IRAS maps around HD 97048 and 97300], Assendorp, R.; Wesselius, P. R.; Prusti, T.; Whittet, D. C. B., 1990
[http://ulisse.pd.astro.it/Astro/ADPS/Systems/Sys_093/index_093.html ADPS]
[http://data.darkenergysurvey.org/aux/releasenotes/DESDMrelease.html DES]
[http://ulisse.pd.astro.it/Astro/ADPS/Systems/Sys_032/index_032.html ADPS]
(2010). "Gaia broad band photometry". Astronomy and Astrophysics.
"GALEX Instrument Summary". Goddard Space Flight Center.
"HAWC".
[http://irtfweb.ifa.hawaii.edu/~nsfcam2/Welcome.html NSFCAM]
"ISAAC Overview". ESO.
LSST filter characteristics taken from https://github.com/lsst/throughputs/blob/master/baseline/ (see the filter_''X''.dat files) with the limits at half the peak transmission.
[http://heasarc.gsfc.nasa.gov/docs/integral/inthp_about.html About INTEGRAL]
(2012). "THE Pan-STARRS1 PHOTOMETRIC SYSTEM". The Astrophysical Journal.
(2006). "Calibration of the PRONAOS/SPM submillimeter photometer". Astronomy & Astrophysics.
[https://web.archive.org/web/20061001002157/http://heasarc.nasa.gov/W3Browse/all/msxpsc.html MSXPSC – Midcourse Space Experiment (MSX) Point Source Catalog, V2.3]
[https://xmm-tools.cosmos.esa.int/external/xmm_user_support/documentation/uhb/omfilters.html XMM-Newton User's Handbook Sect. 3.5.3.1]
(2007). "The XMM-Newton Optical Monitor survey of the Taurus molecular cloud". Astronomy & Astrophysics.
"Light wavelength to RGB Converter".

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