Iris 1.0 Features

NED Data Access

The Iris SED analysis tool allows the astronomer to search the VO-registered NED astronomical database for SED data available for an extragalactic source of interest, as an alternative to loading data from file into the application. SED data from NED may be directly imported into Iris while starting the application from the command line, by adding a query which specifies an object name to use as an identifier in the search of NED.

% <basedir>/iris-1.0-<plat>-<arch>/Iris "http://vo.ned.ipac.caltech.edu/services/accessSED\?REQUEST=getData\&TARGETNAME=3c273"

The "Loading SED Data into Iris" section of the Iris How-to Guide provides instruction and further details on this feature.

Data Visualization and Customization

As the Iris user interface is an adaptation of the Specview spectral visualization and analysis interface, it is equipped with many of the data display preferences offered by Specview. Most notably, one can build a wide-band SED for a source by overplotting or combining data taken with different instruments and/or spectral bands.

The "Visualizing SED Data" section of the Iris How-to Guide describes the various options available for displaying and customizing SED data in Iris, and the "Saving SED Data" section includes instructions for saving user-set preferences.

Spectral Model Fitting

Iris allows for robust modeling and fitting of SED data through association with Sherpa, an extensible, Python-based, multi-waveband modeling and fitting application for astronomers.

Within Iris, the user is provided with an extensive list of emission and absorption models from which to choose for building custom model expressions for fitting, as well as a variety of fit statistics and optimization methods.

The best-fit SED model parameter values, and confidence limits on them, returned by a fit in Iris, may be saved to file. The "Modeling and Fitting SED Data" section of the Iris How-to Guide describes the features of the Iris Fit function, including instructions on defining model expressions, setting initial model parameter values and ranges, choosing an appropriate fit statistic and method, and saving fit parameters.

Conversion Tool for Unsupported Data Formats

The SED Importer tool - which is a GUI run separately from the Iris GUI, but will be included in the main application in a future release - is available for converting user SED data files into a format supported by Iris, either VOTable or FITS. Files in any of the following formats may be input to the tool for conversion: ASCII, CSV, FITS (non-standard), VOTable (non-standard), IPAC, TST.

Multiple, separate SED data segments may be loaded into the SED Importer, in various formats, and saved together as an aggregate SED file in one of the aforementioned supported formats; the resulting SED file may be uploaded into Iris for analysis. The "Converting SED Data to IVOA/Iris Format" section of the Iris How-to Guide describes the features of the SED Importer tool.