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(Abridged) In this paper, multi-wavelength data are compiled for a sample of 1425 Fermi blazars to calculate their spectral energy distributions (SEDs). A parabolic function, $log( u F_{ u}) = P_1(log u - P_2)^2 + P_3,$ is used for SED fitting. Synchrotron peak frequency ($log u_p$), spectral curvature ($P_1$), peak flux ($ u_{rm p}F_{rm u_p}$), and integrated flux ($ u F_{ u}$) are successfully obtained for 1392 blazars (461 flat spectrum radio quasars-FSRQs, 620 BL Lacs-BLs and 311 blazars of uncertain type-BCUs, 999 sources have known redshifts). Monochromatic luminosity at radio 1.4 GHz, optical R band, X-ray at 1 keV and $gamma$-ray at 1 GeV, peak luminosity, integrated luminosity and effective spectral indexes of radio to optical ($alpha_{rm RO}$), and optical to X-ray ($alpha_{rm OX}$) are calculated. The Bayesian classification is employed to log$ u_{rm p}$ in the rest frame for 999 blazars with available redshift and the results show that 3 components are enough to fit the $log u_{rm p}$ distribution, there is no ultra high peaked subclass. Based on the 3 components, the subclasses of blazars using the acronyms of Abdo et al. (2010a) are classified, and some mutual correlations are also studied. Conclusions are finally drawn as follows: (1) SEDs are successfully obtained for 1392 blazars. The fitted peak frequencies are compared with common sources from samples available (Sambruna et al. 1996, Nieppola et al. 2006, 2008, Abdo et al. 2010a). (2) Blazars are classified as low synchrotron peak sources (LSPs) if $log u_{rm p}$(Hz) $leq 14.0$, intermediate synchrotron peak sources (ISPs) if $14.0 < log u_{rm p}$(Hz) $leq 15.3$, and high synchrotron peak sources (HSPs) if $log u_{rm p}$(Hz) $> 15.3$. (3) $gamma$-ray emissions are strongly correlated with radio emissions. (...)
(Abridged) We have conducted a detailed investigation of the broad-band spectral properties of the gamma-ray selected blazars of the Fermi LAT Bright AGN Sample (LBAS). By combining our accurately estimated Fermi gamma-ray spectra with Swift, radio,
We present multiwavelength spectral analyses of two Fermi-LAT blazars, OJ 287 and 3C 279, that are part of the Boston University multiwaveband polarization program. The data have been compiled from observations with Fermi, RXTE, the VLBA, and various
We present a determination of the distributions of gamma-ray photon flux -- the so called LogN-LogS relation -- and photon spectral index for blazars, based on the third extragalactic source catalog of the Fermi Gamma-ray Space Telescopes Large Area
We collect data from the radio to the gamma-ray range for three complete samples of blazars: the Slew Survey and the 1Jy samples of BL Lacs and the 2Jy sample of Flat Spectrum Radio-Loud Quasars (FSRQs). The fraction of objects detected in gamma-rays
The GeV break in spectra of the blazar 3C 454.3 is a special observation feature that has been discovered by the {it Fermi}-LAT. The origin of the GeV break in the spectra is still under debate. In order to explore the possible source of GeV spectral