Iris: The VAO SED Application

Stephen Doe (Smithsonian Astrophysical Observatory), S. Doe (SAO), N. Bonaventura (SAO), I. Busko (STScI), M. Cresitello-Dittmar (SAO), R. D'Abrusco (SAO), R. Ebert (IPAC), J. Evans (SAO), O. Laurino (SAO), J. McDowell, (SAO), O. Pevunova (IPAC), B. Refsdal (SAO)


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 seamlessly combines key features of several existing astronomical software applications to streamline and enhance the SED analysis process. With Iris, users may read in 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 (the NASA Extragalactic Database). Data written in unsupported formats may be converted for upload using SEDImporter, a new application provided with the package.

The components of Iris have been contributed by members of the VAO. Specview, contributed by STScI (the Space Telescope Science Institute), provides a GUI for reading, editing, and displaying SEDs, as well as defining model expressions and setting initial model parameter values. Sherpa, contributed by the Chandra project at SAO (the Smithsonian Astrophysical Observatory), provides a library of models, fit statistics, and optimization methods for analyzing SEDs; 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 (the Infrared Processing and Analysis Center) at Caltech for easy location of data for a given extragalactic astronomical 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. We also demonstrate the use of Iris to read, display, select data 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.

Slides in PDF format

Paper ID: F3

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