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).[lower-alpha 1] 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.[lower-alpha 2]

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[2]		 Full width at half maximum[2]
[lower-alpha 3] (archetypal Bandwidth) (Δλ)[lower-alpha 4]		 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[3] 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 900 nm[4] 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[5] 5800 nm[5] Q'

Note: colors are only approximate and based on wavelength to sRGB representation (when possible).[6]

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.[7]

Filters used

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[8]
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[9]
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 the Dark Energy Survey[10]
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[11]
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)[12]
GALEX[13] 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+ for SOFIA[14]
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[15]
ISAAC UTI/VLT[16] 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)[17] 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[18] on INTEGRAL
Pan-STARRS g = 481 nm r = 617 nm i = 752 nm z = 866 nm y = 962 nm Panoramic Survey Telescope And Rapid Response System[19]
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[20]
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[21]
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 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 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 Monitor[22]
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[23]

Note: colors are only approximate and based on wavelength to sRGB representation (when possible).[24]


See also

References and footnotes

  1. ↑ Spectral Colors
  2. 1 2 Binney, J.; Merrifield M. Galactic Astronomy, Princeton University Press, 1998, ch. 2.3.2, pp. 53
  3. ↑ Bessell, Michael S. (September 2005). "Standard Photometric Systems" (PDF). Annual Review of Astronomy and Astrophysics. 43 (1): 293–336. Bibcode:2005ARA&A..43..293B. doi:10.1146/annurev.astro.41.082801.100251. ISSN 0066-4146.
  4. ↑ Gouda, N.; Yano, T.; Kobayashi, Y.; Yamada, Y.; et al. (23 May 2005). "JASMINE: Japan Astrometry Satellite Mission for INfrared Exploration". Proceedings of the International Astronomical Union. 2004 (IAUC196): 455–468. Bibcode:2005tvnv.conf..455G. doi:10.1017/S1743921305001614. S2CID 123261288. z-band: 0.9 μm
  5. 1 2 Handbook of Geophysics and the Space Environment 1985, Air Force Geophysics Laboratory, 1985, ed. Adolph S. Jursa, Ch. 25, Table 25-1
  6. ↑ "Light wavelength to RGB Converter". www.johndcook.com. Retrieved 2023-07-28.
  7. ↑ Monson, Andrew J.; Pierce, Michael J. (2011). "Near-Infrared (Jhk) Photometry of 131 Northern Galactic Classical Cepheids". The Astrophysical Journal Supplement Series. 193 (1): 12. Bibcode:2011ApJS..193...12M. doi:10.1088/0067-0049/193/1/12. Example of use of J for "near-infrared"
  8. ↑ 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
  9. ↑ ADPS
  10. ↑ DES
  11. ↑ ADPS
  12. ↑ Jordi, C.; Gebran, M.; Carrasco, J. M.; de Bruijne, J.; Voss, H.; Fabricius, C.; Knude, J.; Vallenari, A.; Kohley, R.; Mora, A. (2010). "Gaia broad band photometry". Astronomy and Astrophysics. 523: A48. arXiv:1008.0815. Bibcode:2010A&A...523A..48J. doi:10.1051/0004-6361/201015441. S2CID 34033669.
  13. ↑ "GALEX Instrument Summary". Goddard Space Flight Center. Retrieved 5 June 2019.
  14. ↑ "HAWC". Archived from the original on 2008-03-13. Retrieved 2008-05-25.
  15. ↑ NSFCAM
  16. ↑ "ISAAC Overview". Paranal Instrumentation. ESO. Retrieved 13 October 2011.
  17. ↑ 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.
  18. ↑ About INTEGRAL
  19. ↑ Tonry, J. L.; Stubbs, C. W.; Lykke, K. R.; Doherty, P.; Shivvers, I. S.; Burgett, W. S.; Chambers, K. C.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R.-P.; Magnier, E. A.; Morgan, J. S.; Price, P. A.; Wainscoat, R. J. (2012). "THE Pan-STARRS1 PHOTOMETRIC SYSTEM". The Astrophysical Journal. 750 (2): 99. arXiv:1203.0297. Bibcode:2012ApJ...750...99T. doi:10.1088/0004-637X/750/2/99. S2CID 119266289.
  20. ↑ Pajot, F.; Stepnik, B.; Lamarre, J.-M.; Bernard, J.-P.; Dupac, X.; Giard, M.; Lagache, G.; Leriche, B.; Meny, C.; Recouvreur, G.; Renault, J.-C.; Rioux, C.; Ristorcelli, I.; Serra, G.; Torre, J.-P. (2006). "Calibration of the PRONAOS/SPM submillimeter photometer" (PDF). Astronomy & Astrophysics. 447 (2): 769–781. Bibcode:2006A&A...447..769P. doi:10.1051/0004-6361:20034226. S2CID 4822401.
  21. ↑ MSXPSC – Midcourse Space Experiment (MSX) Point Source Catalog, V2.3
  22. ↑ XMM-Newton User's Handbook Sect. 3.5.3.1
  23. ↑ Audard, M.; Briggs, K. R.; Grosso, N.; Güdel, M.; Scelsi, L.; Bouvier, J.; Telleschi, A. (2007). "The XMM-Newton Optical Monitor survey of the Taurus molecular cloud". Astronomy & Astrophysics. 468 (2): 379–390. arXiv:astro-ph/0611367. Bibcode:2007A&A...468..379A. doi:10.1051/0004-6361:20066320. S2CID 59479808.
  24. ↑ "Light wavelength to RGB Converter". www.johndcook.com. Retrieved 2023-07-28.
  1. ↑ Indigo and cyan are not standard colors.[1] Orange, yellow, and green fall under visual bands, while violet and purple are in every blue band.
  2. ↑ See Description column of the chart
  3. ↑ 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
  4. ↑ Delta lambda
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