Extended Data Fig. 1: Energy spectra measured with PolarLight.
From: Re-detection and a possible time variation of soft X-ray polarization from the Crab
The solid curves are for the Crab and the dotted are for the background. The background spectra are obtained by observing source-free regions. The red spectra are constructed using all x-ray events passing from particle discrimination and the blue ones consist of events used for polarimetry (with one more criterion on the number of fired pixels). Errors of 1σ are shown on the two Crab spectra. We note that the background events shown in the plot are mainly due to charged particles but can not be distinguished by particle discrimination. A discussion on the time variation and modulation of the background can be found in Methods.
