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#### 10.7.13 KCorrections

Functions for calculating K-corrections.

`kCorr( filter, redshift, colorType, colorValue )`
  Calculates K-corrections. This allows you to determine K-corrections for a galaxy, given its redshift and a colour. Filters for GALEX, SDSS, UKIDSS, Johnson, Cousins and 2MASS are covered.

  To define the calculation you must choose both a filter, specified as a `KCF_*` constant, and a colour (filter pair) specified as a `KCC_*` constant. For each available filter, only certain colours are available, as described in the documentation of the relevant `KCF_*` constant.

  The algorithm used is described at http://kcor.sai.msu.ru/. This is based on the paper "Analytical Approximations of K-corrections in Optical and Near-Infrared Bands" by I.Chilingarian, A.-L.Melchior and I.Zolotukhin (2010MNRAS.405.1409C), but extended to include GALEX UV bands and with redshift coverage up to 0.5 as described in "Universal UV-optical Colour-Colour-Magnitude Relation of Galaxies" by I.Chilingarian and I.Zolotukhin (2012MNRAS.419.1727C).

  - Parameters:
    - `filter` (KFilter): `KCF_*` constant defining the filter for which you want to calculate the K-correction
    - `redshift` (floating point): galaxy redshift; this should be in the range 0-0.5
    - `colorType` (KColor): `KCC_*` constant defining the filter pair for the calculation; check the `KCF_*` constant documentation to see which ones are permitted for a given filter
    - `colorValue` (floating point): the value of the colour
  - Return value
    - (floating point): K correction
  - Examples:
    - `kCorr(KCF_g, 0.16, KCC_gr, -0.8) = 3.593`
    - `kCorr(KCF_FUV, 0.48, KCC_FUVu, 0.31) = -0.170`
`KCF_FUV`
  GALEX FUV filter (AB). Use with KCC_FUVNUV or KCC_FUVu.

`KCF_NUV`
  GALEX NUV filter (AB). Use with KCC_NUVg or KCC_NUVr.

`KCF_u`
  SDSS u filter (AB). Use with KCC_ur, KCC_ui or KCC_uz.

`KCF_g`
  SDSS g filter (AB). Use with KCC_gr, KCC_gi or KCC_gz.

`KCF_r`
  SDSS r filter (AB). Use with KCC_gr or KCC_ur.

`KCF_i`
  SDSS i filter (AB). Use with KCC_gi or KCC_ui.

`KCF_z`
  SDSS z filter (AB). Use with KCC_rz, KCC_gz or KCC_uz.

`KCF_Y`
  UKIDSS Y filter (AB). Use with KCC_YH or KCC_YK.

`KCF_J`
  UKIDSS J filter (AB). Use with KCC_JK or KCC_JH.

`KCF_H`
  UKIDSS H filter (AB). Use with KCC_HK or KCC_JH.

`KCF_K`
  UKIDSS K filter (AB). Use with KCC_JK or KCC_HK.

`KCF_U`
  Johnson U filter (Vega). Use with KCC_URc.

`KCF_B`
  Johnson B filter (Vega). Use with KCC_BRc or KCC_BIc.

`KCF_V`
  Johnson V filter (Vega). Use with KCC_VIc or KCC_VRc.

`KCF_Rc`
  Cousins Rc filter (Vega). Use with KCC_BRc or KCC_VRc.

`KCF_Ic`
  Cousins Ic filter (Vega). Use with KCC_VIc.

`KCF_J2`
  2MASS J filter (Vega). Use with KCC_J2Ks2 or KCC_J2H2.

`KCF_H2`
  2MASS H filter (Vega). Use with KCC_H2Ks2 or KCC_J2H2.

`KCF_Ks2`
  2MASS Ks filter (Vega). Use with KCC_J2Ks2 or KCC_H2Ks2.

`KCC_BIc`
  Johnson B - Cousins Ic colour.

`KCC_BRc`
  Johnson B - Cousins Rc colour.

`KCC_FUVNUV`
  GALEX FUV - NUV colour.

`KCC_FUVu`
  GALEX FUV - SDSS u colour.

`KCC_gi`
  SDSS g - i colour.

`KCC_gr`
  SDSS g - r colour.

`KCC_gz`
  SDSS g - z colour.

`KCC_H2Ks2`
  2MASS H - Ks colour.

`KCC_HK`
  UKIDSS H - K colour.

`KCC_J2H2`
  2MASS J - H colour.

`KCC_J2Ks2`
  2MASS J - Ks colour.

`KCC_JH`
  UKIDSS J - H colour.

`KCC_JK`
  UKIDSS J - K colour.

`KCC_NUVg`
  GALEX NUV - SDSS g colour.

`KCC_NUVr`
  GALEX NUV - SDSS r colour.

`KCC_rz`
  SDSS r - SDSS z colour.

`KCC_ui`
  SDSS u - SDSS i colour.

`KCC_URc`
  Johnson U - Cousins Rc colour.

`KCC_ur`
  SDSS u - r colour.

`KCC_uz`
  SDSS u - z colour.

`KCC_VIc`
  Johnson V - Cousins Ic colour.

`KCC_VRc`
  Johnson V - Cousins Rc colour.

`KCC_YH`
  UKIDSS Y - H colour.

`KCC_YK`
  UKIDSS Y - K colour.

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STILTS - Starlink Tables Infrastructure Library Tool Set
Starlink User Note256
STILTS web page: http://www.starlink.ac.uk/stilts/
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