Inastronomy, aphotometric system is a set of well-definedpassbands (oroptical 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 ofprimary standard stars is provided.
A commonly adopted standardized photometric system is the Johnson-Morgan orUBV photometric system (1953). At present, there are more than 200 photometric systems.[1]
Photometric systems are usually characterized according to the widths of their passbands:
Each letter designates a section of light of theelectromagnetic 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).[a] The letters are not standards, but are recognized by common agreement amongastronomers andastrophysicists.
The use of U,B,V,R,I bands dates from the 1950s, being single-letter abbreviations.[b]
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 | Effective Wavelength Midpoint λeff for Standard Filter[3] | Full width at half maximum[3] [c] (archetypal Bandwidth) (Δλ)[d] | 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. |
| G[4] | 464 nm | 128 nm | g, g' | "G" stands for green. |
| V | 551 nm | 88 nm | v, v' | "V" stands for 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-s' | 893.2 nm | 100 nm | z-s' | |
| Z | 900 nm[5] | 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[6] | 5800 nm[6] | Q' | |
Note: colors are only approximate and based on wavelength to sRGB representation (when possible).[7]
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 manypapers.[8]
The filters currently being used by other telescopes or organizations.
Units of measurements:
| 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[9] | |
| 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 ofNOAO | |||||
| Cousins RI photometry | Rc = 647 nm | Ic = 786.5 nm | Cousins RI photometry, 1976[10] | |||||||
| the Dark Energy Camera | g = 472.0 nm | r = 641.5 nm | i = 783.5 nm | z = 926.0 nm | Y = 1009.5 nm | Central wavelengths for bands in theDark Energy Survey[11] | ||||
| 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[12] | |||||||
| 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 | |||||
| Gaia | G = 673 nm | GBP = 532 nm | GRP = 797 nm | GRVS = 860 nm | Gaia (spacecraft)[13] | |||||
| GALEX[14] | NUV = 175–280 nm | FUV = 135–175 nm | 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 = 89 μm | Band 3 = 154 μm | Band 4 = 214 μm | High-resolution Airborne Wideband Camera+ forSOFIA[15] | |||||
| HDF | 300 nm | 450 nm | 606 nm | 814 nm | Hubble Deep Field from theHubble 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[16] |
| ISAAC UTI/VLT[17] | 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 | ||||||
| Vera C. Rubin Observatory (LSST)[18] | u = 320.5–393.5 nm | g = 401.5–551.9 nm | r = 552.0–691.0 nm | i = 691.0–818.0 nm | z = 818.0–923.5 nm | y = 923.8–1084.5 nm | Vera C. Rubin Observatory | |||
| OMC | Johnson V-filter = 500-580 nm | Optical Monitor Camera[19] onINTEGRAL | ||||||||
| Pan-STARRS | g = 481 nm | r = 617 nm | i = 752 nm | z = 866 nm | y = 962 nm | Panoramic Survey Telescope And Rapid Response System[20] | ||||
| 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[21] | |||||
| 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 onMidcourse Space Experiment[22] | |||
| Spitzer IRAC | ch1 = 3.6 μm | ch2 = 4.5 μm | ch3 = 5.8 μm | ch4 = 8.0 μm | Infrared Array Camera onSpitzer 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 | S = 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 | W1 = 3.4 μm | W2 = 4.6 μm | W3 = 12 μm | W4 = 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 Monitor[23] | |||
| 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 of2MASS withXMM-Newton OM[24] |
Note: colors are only approximate and based on wavelength tosRGB representation (when possible).[25]
z-band: 0.9 μm
