Refined associations of Fermi/LAT sources

Since they were released, many follow up observations of unidentified {gamma}-ray sources have been performed and new procedures for associating {gamma}-ray sources with potential counterparts at other wavelengths have been developed.

Here we review and characterize all of the associations as published in the 1FGL and 2FGL catalogs on the basis of multifrequency archival observations. In particular, we located 177 spectra for the low-energy counterparts that were not listed in the previous Fermi catalogs, and in addition we present new spectroscopic observations of eight {gamma}-ray blazar candidates. Based on our investigations, we introduce a new counterpart category of "candidate associations" and propose a refined classification for the candidate low-energy counterparts of the Fermi sources.