Hi Sindh,

A requirements catalog should be produced as soon as you start gathering and documenting requirements. The purpose of the catalog is to track, monitor and manage your requirements and to enable traceability as the project moves forward. So you build the catalog as soon as you have requirements of any type or level to track and manage. At a high level, you may be tracking features or stakeholder needs (or epics on an agile project) before you drill down into the detailed requirements.

The catalog does not have to be a separate document, depending on the way that requirements are being captured. If you are using a tool that supports indexing, querying, or reporting of requirements then the catalog can potentially be extracted from existing documentation or repository. (Even a Word table of contents that shows a list of documented requirements could potentially serve as a catalog.)

The person responsible for leading requirements elicitation and management would be responsible for this - so usually the BA.