Wide-field polarimetry


This is an area of active ongoing investigation. Users are advised to first view the page on measurements of the primary beams. While polarisation purity is very good on boresight, performance gradually degrades further away from the pointing centre. Additionally, standard calibration techniques cannot correct for severe effects being generated above 1380 MHz. There are similar caveats at UHF, however the exact limitations are still under investigation.

Until off-axis leakage calibration procedures have been established, it is advised that

  • RM synthesis be limited to frequencies below 1380* MHz

  • polarimetry be limited to < 0.5° from field centre.

More details will follow as our understanding evolves.

Users concerned about polarimetry are welcome to contact the helpdesk for advice on their specific use case.

* It may be possible to push up to 1500 MHz if the field of view is severely restricted. Please consult the documentation on the primary beam measurements.