1. Introduction
2. The BAT Telescope
3. Survey Data Set and Screening Criteria
4. Methodology
4.1. The Code
4.2. Detection Strategy
4.3. Identification Strategy
5. Sky Coverage and Limiting Flux
6. The 39-Months Catalogue
6.1. Statistical Properties of the Catalogue
6.2. The Extragalactic Subsample
6.3. $\log(N)-\log(S)$ Distribution
7. Conclusions