BIGCAT is the Broadband Integrated GPU Correlator for ATCA, a project funded in part by an Australian Research Council Linkage Infrastructure, Equipment and Facilities (LIEF) grant. The LIEF funding is being led by Western Sydney University, working closely with CSIRO and seven other university partners. Ray Norris has written an article for The Conversation on the ATCA upgrade, reviewing some of the ATCA’s achievements to date, and outlining what the upgrade will enable.

The BIGCAT project will see the replacement of the CABB (Compact Array Broadband Backend) digitisers and correlator with a hybrid FPGA+GPU backend. BIGCAT will double the instantaneous bandwidth from 4 to 8 GHz, provide a spectral resolution of at least 0.6 kHz, and significantly improve the reliability of the ATCA correlator.  BIGCAT will also provide more flexibility, with many more options for frequency resolution and integration times, the ability to change quickly between different correlator modes, and more adaptable to rapid-response observing. BIGCAT will retain standard CABB features such as mosaicing.

BIGCAT will come with a new version of the ATCA observing program caobs, a new scheduling tool, a new file format (replacing RPFITS with ASDM), and a new archive (moving from ATOA to CASDA). The ASDM (ALMA Science Data Model) data format is a Measurement Set (MS) filesystem which is natively compatible with CASA. Users will be able to use CASA for data processing and analysis, or export to FITS format to be reduced using miriad. Further information and training for observers will be provided as BIGCAT implementation and commissioning progresses.

It is anticipated that BIGCAT will be installed during the 2024OCT semester and will be offered in a shared-risk observing mode after a period of commissioning and verification. BIGCAT will initially support the same observing modes as currently offered by CABB and will be limited to the existing IF setup of 2×2 GHz. Proposers requesting ATCA observations in this semester should prepare observations tables using the current CABB configuration with any technical requirements not captured in the observations table clearly stated in the proposal text. It is anticipated that additional BIGCAT observing modes, including pulsar binning mode and increased bandwidth of 4×2 GHz, will be made available later in the semester.

Further information is available from this presentation to ATUC in April 2024, and updates in the ATNF Daily Astronomy Picture.