Blazars are active galactic nuclei characterized by ultra-luminous broad-band, non-thermal radio to gamma-ray continuum radiation, and by irregular, rapid flux variability across wavebands. They are divided into two subclasses: BL Lac objects and flat spectrum radio quasars (FSRQs). A primary method employed to probe our understanding of these objects is to study their spectral energy distributions (SEDs). Until recently, however, studies of blazar SEDs have been hindered by an insufficient number of simultaneous observations across the spectrum, a critical deficiency with such variable objects. In this thesis, I discuss the data accumulated by an international, long-term, 35-blazar monitoring program led by the Boston University blazar group. By systematically processing these data, I produce SEDs using measurements obtained on average within nine hours per epoch. Sufficient measurements exist within the data set to study the sources in differing states of activity. I propose a definition of quiescent and active states, and extract measurements for epochs during which the sources were either quiescent or active in the gamma-ray regime. For these epochs, I measure the spectral slopes and statistically analyze the relationships between slopes at the different frequency regimes. While the subclasses exhibit some distinct characteristics in the optical and gamma-ray indices when quiescent, these distinctions are significantly less pronounced when the objects are active. The spectral indices for the FSRQs steepen when active in the optical, flatten in the gamma-ray, and remain flat and stable in the X-ray. Generally, BL Lacs exhibit less pronounced changes between states than do the FSRQs.

This thesis treats the findings and current theories of the active galactic nuclei 3454.3. It mainly aims to describe the behavior of the specific source in the gamma-ray energy band as recorded by the Fermi-LAT satellite. Using NASA’s computational tools and all recorded data the variability of the source was assessed. As the received flux from the source varies substantially over time several periods of time for which the flux differs considerably were analysed. Spectral analysis for the various time-frames was performed in order to determine how we best can describe the results from each period. The Fermi-LAT results were then examined in the wider context of multi-wavelength astronomy. Finally, data retrieved at all wavelengths were modeled and compared in accordance with currently held theories.