ann16004 — Announcement

Polarisation angles
26 January 2016
IAU Recommends Convention for Measuring Polarisation Angles

In a letter to the community, the IAU General Secretary Piero Benvenuti, the Presidents of Division B, Piero Ubertini, and Commission B6, Saul J. Adelman, have recommended that all astronomers follow the long-standing convention [1] of measuring polarisation angle in the sense that it increases anti-clockwise when looking at the source. This is in response to concerns arising from the practice amongst some astronomers investigating the polarisation of the Cosmic Microwave Background of measuring polarisation clockwise. If not clearly indicated, this may cause confusion as it results in a change of sign of the U Stokes parameter.

The Recommendation may be viewed here.


  • Recommendation regarding convention for measuring polarisation angles (PDF file 244 KB)


Lars Lindberg Christensen
IAU Press Officer
Garching bei München, Germany
Tel: +49 89 320 06 761
Cell: +49 173 38 72 621

About the Announcement



Polarisation angles