VERITAS Observations of the Blazar H 1426+428

H 1426+428 is an extreme High frequency-peaked BL-Lac (HBL) blazar in the constellation B ̈ootes. An HBL blazar is considered ”extreme” when it has a synchrotron frequency > 10^(17)Hz. H 1426+428 is optically faint but very bright in the X-ray band. VERITAS is an array of four 12m Cherenkov imaging telescopes located at the Fred Lawrence Whipple Observatory (FLWO) near Tucson in Arizona. It is used for gamma ray astronomy in the ∼ 100 GeV – 30 TeV photon energy range, using the Imaging Atmospheric Cherenkov Telescope (IACT) technique, whereby gamma rays that cause particle showers in the earth’s atmosphere are observed via the Cherenkov light produced. VERITAS observed H 1426+428 during an 8 year period of quiescence from 2008-2016 and during a period of higher activity in 2021. In this thesis both sets of VERITAS H 1426+428 data are analysed using VERITAS analysis software VEGAS. Very-high-energy (VHE) spectra are produced and corrected for extragalactic background light (EBL) absorption and light curves are produced on different timescales and investigated for flux variability. Multi-wavelength data was used from two upcoming VERITAS papers to compare the spectral energy distributions for both data sets to a synchrotron self-Compton (SSC) model. It was found that the SSC model could adequately explain both states.