B.1.12 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.