SIA is an implementation of the IVOA Simple Image Access v2 protocol as a FastAPI web service, designed to be deployed as part of the Rubin Science Platform.
The default configuration uses the dax_obscore package and interacts with a Butler repository to find images matching specific criteria. Direct Butler access is not supported, only access via a Remote Butler server.
Query results are streamed to the user as VOTable responses, which is currently the only supported format.
The application expects as part of the configuration a list of Butler Data Collections, each of which expects a number of attributes which define how to access the repository.
The system architecture & design considerations have been documented in SQR-095.
See CHANGELOG.md for the change history of sia.