Stellar X-ray polarimetry

Summary Stellar X-ray polarimetry has for a long time been indicated as a very powerful diagnostic tool. In spite of this widely recognised interest, positive results are limited to just one: the detection, in the now far 1978, of the polarisation of the X-ray emission from the Crab Nebula. Novel-generation experiments promise a wider and richer amount mess of results, at least for strong galactic sources. Polarimetry however, remains an unusually delicate technique that requires a very tight control of systematic effects (at the level of 1% or better) over the very long observing period (10⁵ seconds or more) needed for obtaining a reasonable sensitivity. Paper presented at the 6th Cosmic Physics National Conference, Palermo, 3–7 November 1992.