SVDFIT 1.9.3 - An Eigenvector
Sky Removal Package for IRAF

SVDFIT is an IRAF add-on package developed at the Smithsonian Astrophysical Observatory Telescope Data Center to use Singular Value Decomposition to compute a set of eigenvectors from a large number of spectra and fit them to other spectra for various reasons. Originally, we developed the package to estimate and remove the sky spectrum from spectra without a simultaneous measurement of the sky using a model with multiple eigenvectors. We have also used it to create radial velocity template spectra from multiple observations of similar objects and to fit combined observed sky spectra to object plus sky spectra for removal of the sky background removal from fiber spectra.

SVDFIT decomposes a set of spectra into eigenvectors and fits a set of those eigenvectors to another spectrum, leaving residuals There are three main tasks in the package:

The latest version is available in IRAF SPP source code via ftp at
or via http at

Binary executables for Linux and Solaris are available at

Our technique is described in a paper published in the April 20 2000 issue of The Astropysical Journal Letters, which is available through the ADS at

Here is the history of modifications to this package.

Last updated 14 May 2010 by Doug Mink

[Other SAO/TDC IRAF Packages]