POlarization Sky Survey of the Universe’s Magnetism (POSSUM)

POSSUM is a key survey with the Australian SKA Pathfinder (ASKAP), operating as the commensal polarization counterpart to the (EMU) and (WALLABY) surveys. POSSUM data (after the science-ready processing pipeline) are at 20 arcsecond angular resolution and 1 MHz frequency resolution, covering the frequency ranges of 800 – 1088 MHz ("band 1", covering 2pi steradians of sky between -90° and up to -11 deg to +8 deg, depending on RA) and 1296 – 1440 MHz ("band 2", covering 1.5pi steradians of sky between approximately -65 deg and +15 deg declination). We aim to provide polarization information on all EMU cataloged source components, with approximately 700 000 significant detections expected, as well as maps of polarization properties across the survey area. Full survey observations began in May 2023 and are expected to continue for 5 years.

Our data products in the CADC collection include Stokes I,Q, and U channel cubes, Stokes I multi-frequency synthesis images (at the same resolution and pixel grid as the cubes), 3D RM synthesis cubes, and 2D map of various derived polarization properties. Other data products, including our source polarization and rotation measure catalogs, spectra, and Faraday dispersion functions, are available through other storage systems. The original observations from which all these products are derived are available through the CSIRO ASKAP Science Data Archive (CASDA). Access to POSSUM derived products is provided as part of the Canadian Initiative for Radio Astronomy Data Analysis (CIRADA) program led by a consortium of Canadian universities, in partnership with NRAO and the Canadian Astronomy Data Centre (CADC), and funded by the Canada Foundation for Innovation.


Publications that use data from POSSUM should include a statement as follows:

This scientific work uses data obtained from Inyarrimanha Ilgari Bundara / the Murchison Radio-astronomy Observatory. We acknowledge the Wajarri Yamaji People as the Traditional Owners and native title holders of the Observatory site. The Australian SKA Pathfinder is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is managed by CSIRO. Operation of ASKAP is funded by the Australian Government with support from the National Collaborative Research Infrastructure Strategy. ASKAP uses the resources of the Pawsey Supercomputing Centre. Establishment of ASKAP, the Murchison Radio-astronomy Observatory and the Pawsey Supercomputing Centre are initiatives of the Australian Government, with support from the Government of Western Australia and the Science and Industry Endowment Fund. The POSSUM project (https://possum-survey.org) has been made possible through funding from the Australian Research Council, the Natural Sciences and Engineering Research Council of Canada, the Canada Research Chairs Program, and the Canada Foundation for Innovation.
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