SNEx
About
SNEx (SuperNova Extrapolation) is a tool that makes use of principal component analysis (PCA) performed on a data set of Carnegie Supernova Project (CSP) I & II optical and near-infrared (NIR) spectra to extrapolate optical spectra of Type Ia SNe into the NIR, up to about 2.3 microns.
Essentially, PCA is performed on a set of optical+NIR data to get a set of eigenvectors that span both wavelength regimes. This software takes an input optical spectrum, projects it onto the eigenvectors, and the result allows for a prediction in the NIR. For more detail on how this extrapolation procedure works, see the publication by Burrow et al. (2024).
Example
Below is an example of the extrapolation procedure at work for an example spectrum. Using the information from the original spectrum between the two dashed lines, an extrapolated spectrum (in the red) is achieved.
Extrapolation of a maximum-light spectrum of SN 2011fe.