The Third MIT--Green Bank 5 GHz Survey

The MIT-Green Bank III (MG III) 5 GHz survey covers 1.11 sr of sky in the right ascension range 16.5^h^-5^h^ between +17^deg^ and +39.15^deg^ declination (B1950). The final MG III catalog contains 4761 sources detected with a signal-to-noise ratio > 5. The catalog was produced from two separate north and south surveys with the National Radio Astronomy Observatory (NRAO)^3^ 91 m transit telescope. The north survey was produced from data collected while scanning the telescope north from +19.0^deg^ to +39.15^deg^ declination, and the south survey from data collected from scans from +37.15^deg^ to +17^deg^ declination. The completeness and reliability of the final source list is checked by examination of north and south source lists in a twice observed comparison region, lying between +19.15^deg^ and +37^deg^ and below -10^deg^ Galactic latitude. The comparison region covers 0.569 sr of sky and contains 2412 sources. In this region, the MG III catalog contains 917 sources brighter than 90 mJy and is shown to be 99.8 +/- 0.4% complete at this flux density level. Spectral indices are computed for sources identified in the NRAO 1400 MHz Survey (published by Condon and Broderick). A comparison of the spectral index distributions below -10^deg^ and between +/- 10^deg^ Galactic latitude is presented.