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redcorr analysis.nebular



redcorr -- Correct line flux for interstellar reddening.


redcorr wave flux


This task corrects the input flux for the effects of interstellar reddening. The reddening corrected line flux "I" is derived from the input line flux "F" by:

				{-c * f(lambda)}
	  I(line) = F(line) * 10 

where "c" is the extinction constant (i.e. the logarithmic extinction at H-beta, 4861 Ang), and "f(lambda)" is derived from one of a few possible extinction functions. The choices for Galactic extinction are: Savage & Mathis (1979), Cardelli, Clayton, & Mathis (1989), and the function of Kaler (1976) which is based on Whitford (1958). The choices for extra-Galactic extinction laws are Howarth (1983) for the LMC, and Prevot et al. (1984) for the SMC.

The task output gives the selected reddening function and the corrected flux. The dereddened flux is also stored in the task parameter "result" for ease of use in CL scripts.


wave = 4861.[real]
Wavelength of emission line, in Angstroms.
flux = 0. [real]
Oberved flux of the emission line.
(red_func = "gal") [string]
Choice of interstellar redding function, which is one of: "gal", "ccm", "jbk", "lmc", or "smc".
(c_ext = 0.) [real]
Value to assume for the extinction constant--i.e., the logarithmic extinction at H(beta) 4861.3 Ang. Note that this value may be negative to "un-correct" the flux.
(result = INDEF) [real]
Result of the calculation--i.e, the redding-corrected flux.
(verbose = no) [boolean]
Print verbose output for each iteration?


1. The observed flux of the [O ii] 3727 Ang doublet, relative to I(H-beta) = 100, is 12.4. Find the unreddened flux if the extinction constant is 0.24, using the reddening function of Seaton (1979).

    cl> redcorr 3727 12.4 c_ext=0.24 red_func=seaton 
    # Redding correction using SEATON function:
      Flux: 14.62217



This auxilliary task was written by R.A. Shaw (STScI). Type "help nlevel" for additional information about how the reddening correction is used throughout the `nebular' package, and for literature references for the reddening functions.



For general information about this package, type "help nebular opt=sysdoc".

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