Photometric system

In astronomy, a photometric system is a set of well-defined passbands (or 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.

The first known 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 particular section of the electromagnetic spectrum; most of these sections fall within the region spanning the near-ultraviolet (NUV), the visible and the majority of the near-infrared (NIR).

Indigo and cyan are not standard colors.^[1] Orange, yellow, and green fall under visual bands, while violet and purple are under the blue bands. The letters are not standards, but are recognized by common agreement among astronomers and astrophysicists.

Filter Letter	Effective Wavelength Midpoint λeff For Standard Filter[2]	Full Width Half Maximum[2] (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	"B" stands for blue.
V	551 nm	88 nm	v, v'	"V" stands for visual.
G			g, g'	"G" stands for green (visual).
R	658 nm	138 nm	r, r', R', Rc, Re, Rj	"R" stands for red.
Near-Infrared
I	806 nm	149 nm	i, i', Ic, Ie, Ij	"I" stands for infrared.
Z	900 nm[3]		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, K^8, 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[4]	5800 nm[4]	Q'

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.^[5]

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	K = 2.19 μm	L' = 3.78 μm	M = 4.66 μm	N1 = 8.36 μm	N2 = 9.67 μm	N3 = 12.89 μm		2.2 m telescope at La Silla, ESO[6]
2MASS/PAIRITEL	J = 1.25 μm	H = 1.65 μm	Ks = 2.15 μm							Two Micron All-Sky Survey, Peters Automated InfraRed Imaging TELescope
CFHTLS (Megacam)	u^* = 374 nm	g' = 487 nm	r' = 625 nm	i' = 770 nm	z' = 890 nm					Canada-France-Hawaii Telescope
Chandra X-ray Observatory	LETG = 0.08-0.2 keV	HETG = 0.4-10 keV								Chandra X-ray Observatory
CTIO	J = 1.20 μm	H = 1.60 μm	K = 2.20 μm	L = 3.50 μm						Cerro Tololo Inter-American Observatory, a division of NOAO
Cousins RI photometry	Rc = 647 nm	Ic = 786.5 nm								Cousins RI photometry, 1976[7]
DENIS	I = 0.79 μm	J = 1.24 μm	K = 2.16 μm							Deep Near Infrared Survey
Eggen RI photometry	Re = 635 nm	Ie = 790 nm								Eggen RI photometry, 1965[8]
FIS	N60 = 65.00 μm	WIDE-S = 90.00 μm	WIDE-L = 145.00 μm	N160 = 160.00 μm						Far-Infrared Surveyor on board, AKARI space telescope
GALEX	NUV = 1800-2750Å	FUV = 1400-1700Å								GALaxy Evolution Explorer
GOODS (Hubble ACS)	B = 435 nm	V = 606 nm	i = 775 nm	z = 850 nm						Advanced Camera for Surveys on the Hubble Space Telescope
HAWC	Band 1 = 53 µm	Band 2 = 88 µm	Band 3 = 155 µm	Band 4 = 215 µm						High-resolution Airborne Wideband Camera for SOFIA[9]
HDF	450 nm	606 nm	814 nm							Hubble Deep Field from the Hubble Space Telescope
IRTF NSFCAM	J = 1.26 µm	H = 1.62 µm	K' = 2.12 µm	Ks = 2.15 µm	K = 2.21 µm	L = 3.50 µm	L' = 3.78 µm	M' = 4.78 µm	M = 4.85 µm	NASA Infrared Telescope Facility NSFCAM[10]
ISAAC UTI/VLT[11]	Js = 1.2 µm	H = 1.6 µm	Ks = 2.2 µm	L = 3.78 µm	Brα = 4.07 µm					Infrared Spectrometer And Array Camera at Very Large Telescope
Johnson system (UBV)	U = 364 nm	B = 442 nm	V = 540 nm							UBV photometric system
OMC	Johnson V-filter = 500-580 nm									Optical Monitor Camera[12] on INTEGRAL
Pan-STARRS	uses the Sloan's g,r,i,z filters plus y = 1005 nm									Panoramic Survey Telescope And Rapid Response System
ProNaOS/SPM	Band 1 = 180-240 µm	Band 2 = 240-340 µm	Band 3 = 340-540 µm	Band 4 = 540-1200 µm						PROgramme NAtional d'Observations Submillerètrique/Systéme Photométrique Multibande, balloon-borne experiment[13]
Sloan, SDSS	u' = 354 nm	g' = 475 nm	r' = 622 nm	i' = 763 nm	z' = 905 nm					Sloan Digital Sky Survey
SPIRIT III	Band B1 = 4.29 μm	Band B2 = 4.35 μm	Band A = 8.28 μm	Band C = 12.13 μm	Band D = 14.65 μm	Band E = 21.34 μm				Infrared camera on Midcourse Space Experiment[14]
Spitzer IRAC	3.6 μm	4.5 μm	5.8 μm	8.0 μm						Infrared Array Camera on Spitzer Space Telescope
Spitzer MIPS	24 μm	70 μm	160 μm							Multiband Imaging Photometer for Spitzer on Spitzer
Stromvil filters	U = 345 nm	P = 374 nm	S = 405 nm	Y = 466 nm	Z = 516 nm	V = 544 nm	S = 656 nm			Stromvil photometry
Strömgren filters	u = 350 nm	v = 411 nm	b = 467 nm	y = 547 nm	β narrow = 485.8 nm	β wide = 485 nm				Strömgren photometric system
UKIDSS (WFCAM)	Z = 882 nm	Y = 1031 nm	J = 1248 nm	H = 1631 nm	K = 2201 nm					UKIRT Infrared Deep Sky Survey
Vilnius photometric system	U = 345 nm	P = 374 nm	X = 405 nm	Y = 466 nm	Z = 516 nm	V = 544 nm	S = 656 nm			Vilnius photometric system
VISTA IRC	Z = 0.88 μm	Y = 1.02 μm	J = 1.25 μm	H = 1.65 μm	Ks = 2.20 μm	NB1.18 = 1.18 μm				Visible & Infrared Survey Telescope for Astronomy
WISE	3.4 μm	4.6 μm	12 μm	22 μm						Wide-field Infrared Survey Explorer
XMM-Newton OM	UVW2 = 212 nm	UVM2 = 231 nm	UVW1 = 291 nm	U = 344 nm	B = 450 nm	V = 543 nm				XMM-Newton Optical/UV Monitoring[15]
XEST Survey	UVW2 = 212 nm	UVM2 = 231 nm	UVW1 = 291 nm	U = 344 nm	B = 450 nm	V = 543 nm	J = 1.25 μm	H = 1.65 μm	Ks = 2.15 μm	Survey includes the point source of 2MASS with XMM-Newton OM[16]

See also

• Photometry
• AB magnitude

References

1. Spectral Colors
2. Binney, J.; Merrifield M. Galactic Astronomy, Princeton University Press, 1998, ch. 2.3.2, pp. 53
3. Gouda, N.; N. Gouda; T. Yano; Y. Kobayashi; et al. (23 May 2005). "JASMINE: Japan Astrometry Satellite Mission for INfrared Exploration". Proceedings of the International Astronomical Union 2004 (IAUC196): 455–468. doi:10.1017/S1743921305001614.
4. Handbook of Geophysics and the Space Environment 1985, Air Force Geophysics Laboratory, 1985, ed. Adolph S. Jursa, Ch. 25, Table 25-1
5. Monson, Andrew J.; Pierce, Michael J. (2011). "Near-Infrared (Jhk) Photometry of 131 Northern Galactic Classical Cepheids". The Astrophysical Journal Supplement Series 193: 12. doi:10.1088/0067-0049/193/1/12. Example of use of J for "near-infrared"
6. 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
7. ADPS
8. ADPS
9. HAWC
10. NSFCAM
11. "ISAAC Overview". Paranal Instrumentation. ESO. Retrieved 13 October 2011.
12. About INTEGRAL
13. Calibration of the PRONAOS/SPM submillimeter photometer, F.Pajot et al. 2006
14. MSXPSC – Midcourse Space Experiment (MSX) Point Source Catalog, V2.3
15. XMM-Newton SAS: Watchout Page
16. The XMM-Newton Optical Monitor Survey of the Taurus Molecular Cloud, M.Audard et al. 2006

External links

1. Johnson, H. L.; Morgan, W. W. (1953), Fundamental stellar photometry for standards of spectral type on the revised system of the Yerkes spectral atlas, The Astrophysical Journal, vol. 117, pp. 313–352
2. The Asiago Database on Photometric Systems
3. Michael S. Bessell (2005), STANDARD PHOTOMETRIC SYSTEMS, Annual Review of Astronomy and Astrophysics vol. 43, pp. 293–336
4. Infrared portrait of the nearby massive star-forming region IRAS 09002-4732, Apai, D.; Linz, H.; Henning, Th.; Stecklum, B., 2005