Removing a Spectrum's Continuum using rvsao.contpars

contpars is an IRAF pset which sets the parameters to be used to fit the continuum of spectra prior to cross-correlation or an emission line search. A pset is basically a free-standing parameter file which can be used by several tasks. In this case, the same parameters are used for both xcsao and emsao. A similar pset, contsum, is used by sumspec. The parameters are used by one subroutine, icsubcon, which is called by all three of the above tasks.

Remove continuum for line search (ICSUBCON)

The IRAF curve fitting subroutines may be used interactively by setting c_interactive to yes. In this case, a graph of the fit and the spectrum is displayed, and the result may be examined or refit after individual pixels are removed. Aq command is needed to exit from the interactive graph.

A function, spline1, spline3, legendre, or chebyshev, which is specified by c_function of order order is used for the continuum fit. The portion of the spectra to be fit is the image section specified by sample, averaged in groups of naverage pixels.

Points outside of limits s_low_reject and s_high_reject, specified in standard deviations of the fit, are eliminated through niterate iterations, with grow pixels rejected on each side of the rejected point at each iteration. If emsao.contsub_plot or xcsao.contsub_plot is yes, the spectrum is plotted with the continuum removed.

[rvsao] [xcsao] [emsao]