BIMA data archive: the architecture and implementation of a real-time telescope archiving system

We describe the design model and implementation of the data archiving system used by the Berkeley-Illinois-Maryland Association (BIMA) millimeter array telescope. This system transmits data in real-time from the BIMA telescope at the Hat Creek Observatory in northern California via the Internet to an archive server at the National Center for Supercomputing Applications (NCSA) in Urbana, Illinois. Once at NCSA, the data undergo minor processing to make it available to astronomers via an HTML interface: (1) the data are checked for successful transmission, (2) metadata are extracted from the data and inserted into a searchable database, and (3) the data are sent to the NCSA mass storage system. When necessary, the system can carry out rollback operations which allow it to easily recover from errors, particularly those associated with the often unstable Internet. We also comment on some ways in which the system can be improved and expanded to adapt to changing observing strategies.