idlastro / Astronomical Utilities: CALZ_UNRED

[Source code]

NAME
CALZ_UNRED
PURPOSE
Deredden a galaxy spectrum using the Calzetti et al. (2000) recipe
EXPLANATION
Calzetti et al.  (2000, ApJ 533, 682) developed a recipe for dereddening 
the spectra of galaxies where massive stars dominate the radiation output,
valid between 0.12 to 2.2 microns.     (CALZ_UNRED extrapolates between
0.12 and 0.0912 microns.)   
CALLING SEQUENCE
CALZ_UNRED, wave, flux, ebv, [ funred, R_V = ]
INPUT
WAVE - wavelength vector (Angstroms)
FLUX - calibrated flux vector, same number of elements as WAVE
         If only 3 parameters are supplied, then this vector will
         updated on output to contain the dereddened flux.
EBV  - color excess E(B-V), scalar.  If a negative EBV is supplied,
         then fluxes will be reddened rather than deredenned.
         Note that the supplied color excess should be that derived for 
         the stellar  continuum, EBV(stars), which is related to the 
         reddening derived from the gas, EBV(gas), via the Balmer 
         decrement by EBV(stars) = 0.44*EBV(gas)
OUTPUT
FUNRED - unreddened flux vector, same units and number of elements
         as FLUX.   FUNRED values will be zeroed outside valid domain
         Calz_unred (0.0912 - 2.2 microns).
OPTIONAL INPUT KEYWORD
R_V - Ratio of total to selective extinction, default = 4.05.  
      Calzetti et al. (2000) estimate R_V = 4.05 +/- 0.80 from optical
      -IR observations of 4 starbursts.
EXAMPLE
Estimate how a flat galaxy spectrum (in wavelength) between 1200 A 
and 3200 A is altered by a reddening of E(B-V) = 0.1.   
IDL> w = 1200 + findgen(40)*50      ;Create a wavelength vector
IDL> f = w*0 + 1                    ;Create a "flat" flux vector
IDL> calz_unred, w, f, -0.1, fnew  ;Redden (negative E(B-V)) flux vector
IDL> plot,w,fnew                   
NOTES
Use the 4 parameter calling sequence if you wish to save the 
        original flux vector.
PROCEDURE CALLS
POLY()
REVISION HISTORY
Written   W. Landsman        Raytheon  ITSS   December, 2000