English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The NRAO VLA Sky Survey (NVSS) Rotation Measure (RM) catalogue has enablednumerous studies in cosmic magnetism, and will continue being a unique datasetcomplementing future polarisation surveys. Robust comparisons with these newsurveys will however require further understandings in the systematic effectspresent in the NVSS RM catalogue. In this paper, we make careful comparisonsbetween our new on-axis broadband observations with the Karl G. Jansky VeryLarge Array and the NVSS RM results for 23 sources. We found that twounpolarised sources were reported as polarised at about 0.5% level in the RMcatalogue, and noted significant differences between our newly derived RMvalues and the catalogue values for the remaining 21 sources. Thesediscrepancies are attributed to off-axis instrumental polarisation in the NVSSRM catalogue. By adopting the 0.5% above as the typical off-axis instrumentalpolarisation amplitude, we quantified its effect on the reported RMs with asimulation, and found that on average the RM uncertainties in the cataloguehave to be increased by $\approx$ 10% to account for the off-axis instrumentalpolarisation effect. This effect is more substantial for sources with lowerfractional polarisation, and is a function of the source's true RM. Moreover,the distribution of the resulting RM uncertainty is highly non-Gaussian. Withthe extra RM uncertainty incorporated, we found that the RM values from the twoobservations for most (18 out of 21) of our polarised targets can bereconciled. The remaining three are interpreted as showing hints of timevariabilities in RM.

A Broadband Spectro-polarimetric View of the NVSS Rotation Measure Catalogue II: Effects of Off-axis Instrumental Polarisation