SKA subarray templates library
The design baseline of the SKA telescopes comprises 197 SKA-Mid dishes and 512 SKA-Low stations, which will be constructed and verified in stages called array assemblies (AA). While many SKA projects will require the enormous sensitivity and imaging quality of the full SKA-Mid or SKA-Low arrays, some projects will not require the full array to meet their scientific goals. To maximise the scientific efficiency, the SKA telescopes can form up to 16 concurrent subarrays for scientific and engineering/maintenance purposes.
At the proposal submission stage, the scientific users will select the appropriate array configuration needed for their science from a predefined subarray templates library. We expect these templates to evolve to match scientific usage and requirements. New subarray templates may be proposed throughout the SKA Observatory's lifetime and, if approved, added to the list of selectable subarray templates.
We have compiled a draft set of the subarray templates, comprising 26 templates for SKA-Mid and 27 for SKA-Low in the two array assemblies (AA* and AA4), which will be available to the science community through regular observing cycles. These templates were defined based on a first round of consultation with members of the SKA Science Working Groups. Based on feedback from the SKA user community, this set of subarray templates is intended to evolve significantly before SKAO commences Science Operations and then more slowly as the Observatory enters full-time operations.
The templates defined in this document have also been incorporated into the subarray simulation tool (a Python package called ska_ost_array_config). This tool allows astronomers to simulate interferometric observations using any of the defined subarray templates and experiment with new template definitions.
In addition to creating subarrays, each SKA Low station can be split into multiple substations. Each substation produces an independent data stream, which can be processed by the SKA Low Correlator and BeamFormer (CBF). Observing in substation mode gives an astronomer access to larger fields of view and short baseline lengths at the cost of instantaneous bandwidth. We have produced a new memo (linked below) which describes the substation mode and defines a few example substation templates.
The memos and the software package can be accessed using the links below:
- SKA Low and Mid Subarray templates memo
- SKA Low Substation templates memo
- Python package (ska_ost_array_config)
- A Jupyter Notebook in the repository provides a more detailed description of the various functionalities available in ska_ost_array_config, particularly how to access the subarray templates library.
Finally, the SKAO is actively seeking input from the SKA user community to ensure that the subarray templates list evolves in step with science planning. We would appreciate it if science community members could respond to this survey, which will help us refine the template definitions. Alternatively, feedback can also be sent to sciops@skao.int.