We carried out a large program with the Karl G. Jansky Very Large Array ( VLA ) : ‘ THOR : The H i , OH , Recombination line survey of the Milky Way ’ . We observed a significant portion ( \sim 100 deg ^ { 2 } ) of the Galactic plane in the first quadrant of the Milky Way in the 21 cm H i line , 4 OH transitions , 19 radio recombination lines , and continuum from 1 to 2 GHz . In this paper we present a catalog of the continuum sources in the first half of the survey ( l = 14.0 - 37.9 \degr and l = 47.1 - 51.2 ° , |b| \leq 1.1 ° ) at a spatial resolution of 10 - 25 \arcsec , depending on the frequency and sky position with a spatially varying noise level of \sim 0 . 3 - 1 mJy beam ^ { -1 } . The catalog contains \sim 4400 sources . Around 1200 of these are spatially resolved , and \sim 1000 are possible artifacts , given their low signal-to-noise ratios . Since the spatial distribution of the unresolved objects is evenly distributed and not confined to the Galactic plane , most of them are extragalactic . Thanks to the broad bandwidth of the observations from 1 to 2 GHz , we are able to determine a reliable spectral index for \sim 1800 sources . The spectral index distribution reveals a double-peaked profile with maxima at spectral indices of \alpha \approx - 1 and \alpha \approx 0 , corresponding to steep declining and flat spectra , respectively . This allows us to distinguish between thermal and non-thermal emission , which can be used to determine the nature of each source . We examine the spectral index of \sim 300 known H ii regions , for which we find thermal emission with spectral indices around \alpha \approx 0 . In contrast , supernova remnants ( SNR ) show non-thermal emission with \alpha \approx - 0.5 and extragalactic objects generally have a steeper spectral index of \alpha \approx - 1 . Using the spectral index information of the THOR survey , we investigate potential SNR candidates . We classify the radiation of four SNR candidates as non-thermal , and for the first time , we provide strong evidence for the SNR origin of these candidates .