Astronomical measurements and data For the sub-nuclear physics there is a database of the Particle Data Group, I was wondering if there was a similar on-line collection for astrophysics, such as energy absorption and emission spectra for different sources.
 A: There are a wide variety of databases covering all sorts of data, and I won't try and list them all here (but I'll list some of the largest ones). There isn't anything as clear-cut as the Particle Data Group because astronomy deals with complex systems (as opposed to the more fundamental particles in sub-nuclear), and there's no saying that the spectrum of source XX won't change tomorrow. Some sources are more transient than others, and it's often possible to estimate a timescale for transience, but there's always the possibility of some unknown effect coming into play or some unresolved source entering the region and wreaking havoc on the status quo.
I think the closest thing to what you're asking about would be virtual observatories. There are a number of organizations/countries with VO projects, here are a few:


*

*USVAO (also a public outreach site)

*SkyView

*EuroVO

*CVO
There are also a few source catalogs maintained by the Centre de Données de Strasbourg (Simbad, Vizier, Aladin) which are quite extensive, and another by NASA called NED.
Some of the largest collections of survey data are SDSS (>1/4 of the sky in 5 bands from about the near-IR to the near-UV with hundreds of millions of objects catalogued, and millions of spectra), 2MASS (all-sky survey in the near-IR), MAST (compendium of catalogs from the Space Telescope Science Institute). The data from the Planck (IR/radio, all sky), Fermi (gamma ray, all sky) and Chandra (x-ray) satellites are (or will be) publicly archived, and many other archives of data from particular telescopes exist as well.
If you're interested in a particular source (or type of source), or a particular waveband, I might be able to recommend a database.
