  We present a panoramic atlas of Spitzer/IRS spectra of extragalactic sources
collected from the recent literature, with value added measurements of their
spectral features obtained in a homogeneous and concise manner. The atlas
covers the full spectrum of the extragalactic universe and includes star
forming galaxies, obscured and unobscured active galaxies, luminous and
ultra-luminous infrared galaxies, and hybrid objects. Measured features such as
the polycyclic aromatic hydrocarbons, the strength of the silicates in emission
or absorption around 9.7 micron, rest-frame monochromatic luminosities or
colours, combined with measurements derived from spectral decomposition, are
used to establish diagnostics that allow for classification of sources, based
on their infrared properties alone. Average templates of the various classes
are also derived. The full atlas with the value added measurements and
ancillary archival data are publicly available at
http://www.denebola.org/atlas, with full references to the original data.
