10.6 Continuum Normalization

Normalizing an object's flux to the continuum response is very useful if you desire to make relative measurements (such as equivalent widths) on a continuum which is a strong function of wavelength. You can interactively measure the continuum, and normalize by either subtraction or division with an arbitrary continuum by using:

NORM,W,F,fnorm,cont,mode 

W	Wavelengths for spectrum to normalize.
F	Fluxes for spectrum to normalize. If the ``fnorm'' parameter is not included, F will be replaced with the normalized fluxes.
fnorm	Optional output normalized spectrum.
cont	Optional output fitted continuum, as specified by the user.
mode	Optional output vector containing the curve fitting information, in the order in which they are listed: Type of normalization (1=division, 2=subtraction) Type of fit (1=``connect the dots'' approximation, 2=polynomial fit, 3=spline fit) Number of continuum points used Degree of polynomial used (polynomial fit only) Coefficients of polynomial used (polynomial fit only) Chi squared (polynomial fit only) Wavelengths of points used for fitting Fluxes of points used for fitting

NORM provides continuum normalization with several fits (straight line segment, polynomial, or cubic spline). You will be prompted for the normalizing continuum by specifying points with the cursor, and asked to select the type of fit (e.g., spline, line segments, etc.).