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CALZ_UNRED

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.

POLY()

## Revision History

Written W. Landsman Raytheon ITSS December, 2000

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