Performance of the XL-Calibur flight in July 2022

Abstract

X-ray polarimeters for astrophysical use have been enthusiastically developed in recent years. X-ray polarization reveals magnetic field structures and/or geometry structures from celestial objects such as a neutron star and a corona surrounding a black hole. The XL-Calibur is a balloon-borne mission to observe the polarization of hard X-rays, 15–80 keV. This mission equips a Compton scattering polarimeter which is placed at the focal point 12 m away from the hard X-ray telescope. The design of our polarimeter has a capability to detect a few % polarization degrees for a 1 Crab-flux source with observing it for 6 hours each day during a week-long flight. The XL-Calibur was launched in July 2022 and flown for about one week from Esrange Space Center in Sweden to the Canadian Northwest Territories.