  The ASDC SED Builder (http://tools.asdc.asi.it/SED/) is a web based program
developed at the ASI Science Data Center to produce and display the Spectral
Energy Distribution (SED) of astrophysical sources. The tool combines data from
several missions and experiments, both ground and space-based, together with
catalogs and archival data. In the current version (v1.3) the obtained SEDs can
be compared with theoretical expectations and with the sensitivity curve of
several widely known instruments. The displayed data can also be fitted to
simple analytical functions. Providing a cosmological redshift, the SED can be
visualized in rest-frame luminosities. The tool provides transparent access to
ASDC-resident catalogs (e.g. Swift, AGILE, Fermi etc.) as well as to external
archives (e.g. NED, 2MASS, SDSS etc.) covering the whole electromagnetic
spectrum, from radio to TeV energies. Proprietary data can also be properly
handled. The intent of this document is to provide a brief description of the
main capabilities of the ASDC SED Builder. Specific details on the graphical
interface and on the functionalities can be found in the appendix to this
document which provides a tutorial to the tool.
