  We present Iris, the VAO (Virtual Astronomical Observatory) application for
analyzing SEDs (spectral energy distributions). Iris is the result of one of
the major science initiatives of the VAO, and the first version was released in
September 2011. Iris combines key features of several existing software
applications to streamline and enhance SED analysis. With Iris, users may read
and display SEDs, select data ranges for analysis, fit models to SEDs, and
calculate confidence limits on best-fit parameters. SED data may be uploaded
into the application from IVOA-compliant VOTable and FITS format files, or
retrieved directly from NED. Data written in unsupported formats may be
converted using SedImporter, a new application provided with Iris. The
components of Iris have been contributed by members of the VAO. Specview,
contributed by STScI, provides a GUI for reading, editing, and displaying SEDs,
as well as defining models and parameter values. Sherpa, contributed by the
Chandra project at SAO, provides a library of models, fit statistics, and
optimization methods; the underlying I/O library, SEDLib, is a VAO product
written by SAO to current IVOA (International Virtual Observatory Alliance)
data model standards. NED is a service provided by IPAC for easy location of
data for a given extragalactic source, including SEDs. SedImporter is a new
tool for converting non-standard SED data files into a format supported by
Iris. We demonstrate the use of SedImporter to retrieve SEDs from a variety of
sources--from the NED SED service, from the user's own data, and from other VO
applications using SAMP (Simple Application Messaging Protocol). We also
demonstrate the use of Iris to read, display, select ranges from, and fit
models to SEDs. Finally, we discuss the architecture of Iris, and the use of
IVOA standards so that Specview, Sherpa, SEDLib and SedImporter work together
seamlessly.
