Array configuration
Starting with the 2025A semester, MWA will be running with 32 receivers, each capable of digitising 8 tiles simultaneously, for a maximum of 256 tiles.
The SHAO receivers handling the tiles in the ‘Phase II compact’ configuration (core tiles, plus hexes, see below), can be configured to run in oversampling mode, to eliminate the artefacts at coarse channel boundaries, but this has some caveats:
When the correlator is running in ‘oversampling’ mode, all of the RRI receivers must be disabled, because the correlator can’t handle a mix of oversampled data (from SHAO and/or NI receivers) and critically sampled data (from RRI receivers). That means at most 128 tiles can be used - the tiles in the ‘Phase II compact’ configuration below.
Changing between ‘oversampling’ and ‘critically sampled’ mode is currently manual, and labour intensive, and will happen during the 2025A semester on a weekly basis, at best, with a cadence depending on the balance between oversampling and non-oversampling time requested for that week/month.
For normal (critically sampled) observations, the correlator will run in 256T mode all the time, with all 32 receivers active. Each observation can be scheduled with whatever subarray is desired for that target. The standard D0006 morning and evening calibrator blocks will be scheduled as full array (256T) observations, so calibrations can be applied to any subarray taken.
See this page for more information, including a link to precise tile locations: https://mwatelescope.atlassian.net/wiki/spaces/MP/pages/666894337/2025A+semester+sub-arrays+and+configuration